Message-ID: <9470258e-544c-ae65-2222-7a28467c7c99@microchip.com>
Date:   Thu, 20 Jan 2022 08:43:33 +0000
From:   <Eugen.Hristev@...rochip.com>
To:     <jacopo@...ndi.org>
CC:     <linux-media@...r.kernel.org>, <robh+dt@...nel.org>,
        <laurent.pinchart@...asonboard.com>, <sakari.ailus@....fi>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <Nicolas.Ferre@...rochip.com>
Subject: Re: [PATCH v3 23/23] media: atmel: atmel-isc: change format
 propagation to subdev into only verification

On 1/12/22 11:21 AM, Jacopo Mondi wrote:
> Hi Eugen


Hi Jacopo,

> 
> On Mon, Dec 13, 2021 at 03:49:40PM +0200, Eugen Hristev wrote:
>> As a top MC video driver, the atmel-isc should not propagate the format to the
>> subdevice.
>> It should rather check at streamon() time if the subdev is properly configured
>> with a compatible format.
>> Removed the whole format finding logic, and reworked the format verification
>> at streamon time, such that the ISC will return an error if the subdevice
>> is not properly configured.
>> With this being done, the module parameter 'sensor_prefered' makes no sense
>> anymore. The ISC should not decide which format the sensor is using. The
>> ISC should only cope with the situation and inform userspace if the streaming
>> is possible in the current configuration.
> 
> Sounds great!
> 
>>
>> Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
>> ---
>> Changes in v3:
>> - clamp to maximum resolution once the frame size from the subdev is found
>>
>>   drivers/media/platform/atmel/atmel-isc-base.c | 271 ++++++++----------
>>   drivers/media/platform/atmel/atmel-isc.h      |   1 +
>>   2 files changed, 126 insertions(+), 146 deletions(-)
>>
>> diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
>> index 31c8e3029eee..00c8c9588a78 100644
>> --- a/drivers/media/platform/atmel/atmel-isc-base.c
>> +++ b/drivers/media/platform/atmel/atmel-isc-base.c
>> @@ -36,11 +36,6 @@ static unsigned int debug;
>>   module_param(debug, int, 0644);
>>   MODULE_PARM_DESC(debug, "debug level (0-2)");
>>
>> -static unsigned int sensor_preferred = 1;
>> -module_param(sensor_preferred, uint, 0644);
>> -MODULE_PARM_DESC(sensor_preferred,
>> -              "Sensor is preferred to output the specified format (1-on 0-off), default 1");
>> -
>>   #define ISC_IS_FORMAT_RAW(mbus_code) \
>>        (((mbus_code) & 0xf000) == 0x3000)
>>
>> @@ -532,7 +527,7 @@ static int isc_enum_fmt_vid_cap(struct file *file, void *priv,
>>         * convert it to any of the formats that we usually can with a
>>         * RAW sensor. Thus, do not advertise them.
>>         */
>> -     if (!isc->config.sd_format ||
>> +     if (isc->config.sd_format &&
> 
> Is this change intentional ?
> 
>>            !ISC_IS_FORMAT_RAW(isc->config.sd_format->mbus_code))
>>                return -EINVAL;
>>
>> @@ -621,20 +616,30 @@ static int isc_try_validate_formats(struct isc_device *isc)
>>                break;
>>        default:
>>        /* any other different formats are not supported */
>> +             v4l2_err(&isc->v4l2_dev, "Requested unsupported format.\n");
>>                ret = -EINVAL;
>>        }
>>        v4l2_dbg(1, debug, &isc->v4l2_dev,
>>                 "Format validation, requested rgb=%u, yuv=%u, grey=%u, bayer=%u\n",
>>                 rgb, yuv, grey, bayer);
> 
> Would it make sense to move this before the switch so that the
> error messages, if any, appear later ?

Actually, no, because the variables rgb, yuv, grey, bayer, are set 
according to what happens in the switch
> 
>>
>> -     /* we cannot output RAW if we do not receive RAW */
>> -     if ((bayer) && !ISC_IS_FORMAT_RAW(isc->try_config.sd_format->mbus_code))
>> +     if ((bayer) &&
>> +         !ISC_IS_FORMAT_RAW(isc->try_config.sd_format->mbus_code)) {
>> +             v4l2_err(&isc->v4l2_dev, "Cannot output RAW if we do not receive RAW.\n");
>>                return -EINVAL;
>> +     }
>>
>> -     /* we cannot output GREY if we do not receive RAW/GREY */
>>        if (grey && !ISC_IS_FORMAT_RAW(isc->try_config.sd_format->mbus_code) &&
>> -         !ISC_IS_FORMAT_GREY(isc->try_config.sd_format->mbus_code))
>> +         !ISC_IS_FORMAT_GREY(isc->try_config.sd_format->mbus_code)) {
>> +             v4l2_err(&isc->v4l2_dev, "Cannot output GREY if we do not receive RAW/GREY.\n");
>>                return -EINVAL;
>> +     }
>> +
>> +     if ((rgb || bayer || yuv) &&
>> +         ISC_IS_FORMAT_GREY(isc->try_config.sd_format->mbus_code)) {
>> +             v4l2_err(&isc->v4l2_dev, "Cannot convert GREY to another format.\n");
>> +             return -EINVAL;
>> +     }
>>
>>        return ret;
>>   }
>> @@ -862,7 +867,7 @@ static void isc_try_fse(struct isc_device *isc,
>>         * If we do not know yet which format the subdev is using, we cannot
>>         * do anything.
>>         */
>> -     if (!isc->try_config.sd_format)
>> +     if (!isc->config.sd_format)
>>                return;
>>
>>        fse.code = isc->try_config.sd_format->mbus_code;
>> @@ -883,180 +888,141 @@ static void isc_try_fse(struct isc_device *isc,
>>        }
>>   }
>>
>> -static int isc_try_fmt(struct isc_device *isc, struct v4l2_format *f,
>> -                     u32 *code)
>> +static int isc_try_fmt(struct isc_device *isc, struct v4l2_format *f)
>>   {
>> -     int i;
>> -     struct isc_format *sd_fmt = NULL, *direct_fmt = NULL;
>>        struct v4l2_pix_format *pixfmt = &f->fmt.pix;
>> -     struct v4l2_subdev_pad_config pad_cfg = {};
>> -     struct v4l2_subdev_state pad_state = {
>> -             .pads = &pad_cfg
>> -             };
>> -     struct v4l2_subdev_format format = {
>> -             .which = V4L2_SUBDEV_FORMAT_TRY,
>> -     };
>> -     u32 mbus_code;
>> -     int ret;
>> -     bool rlp_dma_direct_dump = false;
>> +     unsigned int i;
>>
>>        if (f->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
>>                return -EINVAL;
>>
>> -     /* Step 1: find a RAW format that is supported */
>> -     for (i = 0; i < isc->num_user_formats; i++) {
>> -             if (ISC_IS_FORMAT_RAW(isc->user_formats[i]->mbus_code)) {
>> -                     sd_fmt = isc->user_formats[i];
>> +     isc->try_config.fourcc = isc->user_formats[0]->fourcc;
>> +
>> +     /* find if the format requested is supported */
>> +     for (i = 0; i < isc->controller_formats_size; i++)
>> +             if (isc->controller_formats[i].fourcc == pixfmt->pixelformat) {
>> +                     isc->try_config.fourcc = pixfmt->pixelformat;
>>                        break;
>>                }
>> -     }
>> -     /* Step 2: We can continue with this RAW format, or we can look
>> -      * for better: maybe sensor supports directly what we need.
>> -      */
>> -     direct_fmt = find_format_by_fourcc(isc, pixfmt->pixelformat);
>> -
>> -     /* Step 3: We have both. We decide given the module parameter which
>> -      * one to use.
>> -      */
>> -     if (direct_fmt && sd_fmt && sensor_preferred)
>> -             sd_fmt = direct_fmt;
>> -
>> -     /* Step 4: we do not have RAW but we have a direct format. Use it. */
>> -     if (direct_fmt && !sd_fmt)
>> -             sd_fmt = direct_fmt;
>> -
>> -     /* Step 5: if we are using a direct format, we need to package
>> -      * everything as 8 bit data and just dump it
>> -      */
>> -     if (sd_fmt == direct_fmt)
>> -             rlp_dma_direct_dump = true;
>> -
>> -     /* Step 6: We have no format. This can happen if the userspace
>> -      * requests some weird/invalid format.
>> -      * In this case, default to whatever we have
>> -      */
>> -     if (!sd_fmt && !direct_fmt) {
>> -             sd_fmt = isc->user_formats[isc->num_user_formats - 1];
>> -             v4l2_dbg(1, debug, &isc->v4l2_dev,
>> -                      "Sensor not supporting %.4s, using %.4s\n",
>> -                      (char *)&pixfmt->pixelformat, (char *)&sd_fmt->fourcc);
>> -     }
>> -
>> -     if (!sd_fmt) {
>> -             ret = -EINVAL;
>> -             goto isc_try_fmt_err;
>> -     }
>> -
>> -     /* Step 7: Print out what we decided for debugging */
>> -     v4l2_dbg(1, debug, &isc->v4l2_dev,
>> -              "Preferring to have sensor using format %.4s\n",
>> -              (char *)&sd_fmt->fourcc);
>> -
>> -     /* Step 8: at this moment we decided which format the subdev will use */
>> -     isc->try_config.sd_format = sd_fmt;
>> -
>> -     /* Limit to Atmel ISC hardware capabilities */
>> -     if (pixfmt->width > isc->max_width)
>> -             pixfmt->width = isc->max_width;
>> -     if (pixfmt->height > isc->max_height)
>> -             pixfmt->height = isc->max_height;
>> -
>> -     /*
>> -      * The mbus format is the one the subdev outputs.
>> -      * The pixels will be transferred in this format Sensor -> ISC
>> -      */
>> -     mbus_code = sd_fmt->mbus_code;
>> -
>> -     /*
>> -      * Validate formats. If the required format is not OK, default to raw.
>> -      */
>> -
>> -     isc->try_config.fourcc = pixfmt->pixelformat;
>> -
>> -     if (isc_try_validate_formats(isc)) {
>> -             pixfmt->pixelformat = isc->try_config.fourcc = sd_fmt->fourcc;
>> -             /* Re-try to validate the new format */
>> -             ret = isc_try_validate_formats(isc);
>> -             if (ret)
>> -                     goto isc_try_fmt_err;
>> -     }
>> -
>> -     ret = isc_try_configure_rlp_dma(isc, rlp_dma_direct_dump);
>> -     if (ret)
>> -             goto isc_try_fmt_err;
>> -
>> -     ret = isc_try_configure_pipeline(isc);
>> -     if (ret)
>> -             goto isc_try_fmt_err;
>>
>> -     /* Obtain frame sizes if possible to have crop requirements ready */
>> -     isc_try_fse(isc, &pad_state);
>> -
>> -     v4l2_fill_mbus_format(&format.format, pixfmt, mbus_code);
>> -     ret = v4l2_subdev_call(isc->current_subdev->sd, pad, set_fmt,
>> -                            &pad_state, &format);
>> -     if (ret < 0)
>> -             goto isc_try_fmt_subdev_err;
>> +     /* If we did not find the requested format, we will fallback here */
>> +     pixfmt->pixelformat = isc->try_config.fourcc;
>> +     pixfmt->colorspace = V4L2_COLORSPACE_SRGB;
>> +     pixfmt->field = V4L2_FIELD_NONE;
>>
>> -     v4l2_fill_pix_format(pixfmt, &format.format);
>> +     isc_try_configure_rlp_dma(isc, false);
>>
>>        /* Limit to Atmel ISC hardware capabilities */
>> -     if (pixfmt->width > isc->max_width)
>> -             pixfmt->width = isc->max_width;
>> -     if (pixfmt->height > isc->max_height)
>> -             pixfmt->height = isc->max_height;
>> +     v4l_bound_align_image(&pixfmt->width, 16, isc->max_width, 0,
>> +                           &pixfmt->height, 16, isc->max_height, 0, 0);
>>
>>        pixfmt->field = V4L2_FIELD_NONE;
>>        pixfmt->bytesperline = (pixfmt->width * isc->try_config.bpp_v4l2) >> 3;
>>        pixfmt->sizeimage = ((pixfmt->width * isc->try_config.bpp) >> 3) *
>>                             pixfmt->height;
>>
>> -     if (code)
>> -             *code = mbus_code;
>> +     isc->try_fmt = *f;
>>
>>        return 0;
>> +}
>>
>> -isc_try_fmt_err:
>> -     v4l2_err(&isc->v4l2_dev, "Could not find any possible format for a working pipeline\n");
>> -isc_try_fmt_subdev_err:
>> -     memset(&isc->try_config, 0, sizeof(isc->try_config));
>> +static int isc_set_fmt(struct isc_device *isc, struct v4l2_format *f)
>> +{
>> +     isc_try_fmt(isc, f);
>>
>> -     return ret;
>> +     /* make the try configuration active */
>> +     isc->config = isc->try_config;
>> +     isc->fmt = isc->try_fmt;
>> +
>> +     v4l2_dbg(1, debug, &isc->v4l2_dev, "ISC set_fmt to %.4s @%dx%d\n",
>> +              (char *)&f->fmt.pix.pixelformat,
>> +              f->fmt.pix.width, f->fmt.pix.height);
>> +
>> +     return 0;
>>   }
>>
>> -static int isc_set_fmt(struct isc_device *isc, struct v4l2_format *f)
>> +static int isc_validate(struct isc_device *isc)
>>   {
>> +     int ret;
>> +     int i;
>> +     struct isc_format *sd_fmt = NULL;
>> +     struct v4l2_pix_format *pixfmt = &isc->fmt.fmt.pix;
>>        struct v4l2_subdev_format format = {
>>                .which = V4L2_SUBDEV_FORMAT_ACTIVE,
>> +             .pad = isc->remote_pad,
>> +     };
>> +     struct v4l2_subdev_pad_config pad_cfg = {};
>> +     struct v4l2_subdev_state pad_state = {
>> +             .pads = &pad_cfg,
>>        };
>> -     u32 mbus_code = 0;
>> -     int ret;
>>
>> -     ret = isc_try_fmt(isc, f, &mbus_code);
>> +     /* Get current format from subdev */
>> +     ret = v4l2_subdev_call(isc->current_subdev->sd, pad, get_fmt, NULL,
>> +                            &format);
> 
> Ah! Haven't you just said we don't care anymore about the subdev
> format ? :)

We don't ! but we can't stream anything if the sensor streams a format 
that we don't understand do we ?

> 
> Kidding, I might got a bit lost in the logic, but if I look at your
> above isc_try_validate_formats() it seems like an ideal candidate for
> .link_validate() media_entity operation.
> 
> Just to make sure we're on the same page, here's how it should ideally
> look like:
> - set format does care about subdev format. It only checks that the
>    format required from the user is one of the ISC supported one. Ie.
>    no v4l2_subdev_call()
> 
> - as s_stream time your top driver calls media_pipeline_start()
> 
> - media_pipeline_start() walks all the entities in the pipeline and
>    validates the format of connected pads. To validate formats the
>    __media_pipeline_start() functions calls link_validate() on each
>    entity. You should in your driver set

Is this done automatically ? if this would be the case, where all links 
are correctly set, then, in theory, it would not be possible that some 
entities have a format set that is not supported by the other side

> 
>          static const struct media_entity_operations your_media_entity_ops = {
>                  .link_validate = v4l2_subdev_link_validate,
>          };
> 
>    if you want to use the default link validation procedure, or set the
>    callback to your custom validation function, which can behave more
>    or less like isc_try_validate_formats()

Does this mean that I can ask the subdev for the format ?
Or how can I obtain the format on the other side of the link ?
link validate can do this for me ?


Thanks for reviewing,
Eugen
> 
> Does it match your understanding too ?
> 
> Thanks
>     j
> 
> 
> 
>>        if (ret)
>>                return ret;
>>
>> -     v4l2_fill_mbus_format(&format.format, &f->fmt.pix, mbus_code);
>> -     ret = v4l2_subdev_call(isc->current_subdev->sd, pad,
>> -                            set_fmt, NULL, &format);
>> -     if (ret < 0)
>> -             return ret;
>> +     /* Identify the subdev's format configuration */
>> +     for (i = 0; i < isc->num_user_formats; i++)
>> +             if (isc->user_formats[i]->mbus_code == format.format.code) {
>> +                     sd_fmt = isc->user_formats[i];
>> +                     break;
>> +             }
>> +
>> +     /* Check if the format is not supported */
>> +     if (!sd_fmt) {
>> +             v4l2_err(&isc->v4l2_dev,
>> +                      "Current subdevice is streaming a media bus code that is not supported 0x%x\n",
>> +                      format.format.code);
>> +             return -EPIPE;
>> +     }
>> +
>> +     /* At this moment we know which format the subdev will use */
>> +     isc->try_config.sd_format = sd_fmt;
>> +
>> +     /* If the sensor is not RAW, we can only do a direct dump */
>> +     if (!ISC_IS_FORMAT_RAW(isc->try_config.sd_format->mbus_code))
>> +             isc_try_configure_rlp_dma(isc, true);
>>
>>        /* Limit to Atmel ISC hardware capabilities */
>> -     if (f->fmt.pix.width > isc->max_width)
>> -             f->fmt.pix.width = isc->max_width;
>> -     if (f->fmt.pix.height > isc->max_height)
>> -             f->fmt.pix.height = isc->max_height;
>> +     v4l_bound_align_image(&format.format.width, 16, isc->max_width, 0,
>> +                           &format.format.height, 16, isc->max_height, 0, 0);
>>
>> -     isc->fmt = *f;
>> +     /* Check if the frame size is the same. Otherwise we may overflow */
>> +     if (pixfmt->height != format.format.height ||
>> +         pixfmt->width != format.format.width) {
>> +             v4l2_err(&isc->v4l2_dev,
>> +                      "ISC not configured with the proper frame size: %dx%d\n",
>> +                      format.format.width, format.format.height);
>> +             return -EPIPE;
>> +     }
>>
>> +     v4l2_dbg(1, debug, &isc->v4l2_dev,
>> +              "Identified subdev using format %.4s with %dx%d %d bpp\n",
>> +              (char *)&sd_fmt->fourcc, pixfmt->width, pixfmt->height,
>> +              isc->try_config.bpp);
>> +
>> +     /* Reset and restart AWB if the subdevice changed the format */
>>        if (isc->try_config.sd_format && isc->config.sd_format &&
>>            isc->try_config.sd_format != isc->config.sd_format) {
>>                isc->ctrls.hist_stat = HIST_INIT;
>>                isc_reset_awb_ctrls(isc);
>>                isc_update_v4l2_ctrls(isc);
>>        }
>> -     /* make the try configuration active */
>> +
>> +     /* Validate formats */
>> +     ret = isc_try_validate_formats(isc);
>> +     if (ret)
>> +             return ret;
>> +
>> +     /* Obtain frame sizes if possible to have crop requirements ready */
>> +     isc_try_fse(isc, &pad_state);
>> +
>> +     /* Configure ISC pipeline for the config */
>> +     ret = isc_try_configure_pipeline(isc);
>> +     if (ret)
>> +             return ret;
>> +
>>        isc->config = isc->try_config;
>>
>>        v4l2_dbg(1, debug, &isc->v4l2_dev, "New ISC configuration in place\n");
>> @@ -1064,6 +1030,19 @@ static int isc_set_fmt(struct isc_device *isc, struct v4l2_format *f)
>>        return 0;
>>   }
>>
>> +static int isc_streamon(struct file *file, void *priv, enum v4l2_buf_type bt)
>> +{
>> +     struct isc_device *isc = video_drvdata(file);
>> +     int ret;
>> +
>> +     ret = isc_validate(isc);
>> +
>> +     if (ret)
>> +             return ret;
>> +
>> +     return vb2_ioctl_streamon(file, priv, bt);
>> +}
>> +
>>   static int isc_s_fmt_vid_cap(struct file *file, void *priv,
>>                              struct v4l2_format *f)
>>   {
>> @@ -1080,7 +1059,7 @@ static int isc_try_fmt_vid_cap(struct file *file, void *priv,
>>   {
>>        struct isc_device *isc = video_drvdata(file);
>>
>> -     return isc_try_fmt(isc, f, NULL);
>> +     return isc_try_fmt(isc, f);
>>   }
>>
>>   static int isc_enum_input(struct file *file, void *priv,
>> @@ -1176,7 +1155,7 @@ static const struct v4l2_ioctl_ops isc_ioctl_ops = {
>>        .vidioc_dqbuf                   = vb2_ioctl_dqbuf,
>>        .vidioc_create_bufs             = vb2_ioctl_create_bufs,
>>        .vidioc_prepare_buf             = vb2_ioctl_prepare_buf,
>> -     .vidioc_streamon                = vb2_ioctl_streamon,
>> +     .vidioc_streamon                = isc_streamon,
>>        .vidioc_streamoff               = vb2_ioctl_streamoff,
>>
>>        .vidioc_g_parm                  = isc_g_parm,
>> @@ -1879,7 +1858,7 @@ static int isc_set_default_fmt(struct isc_device *isc)
>>        };
>>        int ret;
>>
>> -     ret = isc_try_fmt(isc, &f, NULL);
>> +     ret = isc_try_fmt(isc, &f);
>>        if (ret)
>>                return ret;
>>
>> diff --git a/drivers/media/platform/atmel/atmel-isc.h b/drivers/media/platform/atmel/atmel-isc.h
>> index c2cb805faff3..7081698adddd 100644
>> --- a/drivers/media/platform/atmel/atmel-isc.h
>> +++ b/drivers/media/platform/atmel/atmel-isc.h
>> @@ -297,6 +297,7 @@ struct isc_device {
>>        struct completion       comp;
>>
>>        struct v4l2_format      fmt;
>> +     struct v4l2_format      try_fmt;
>>        struct isc_format       **user_formats;
>>        unsigned int            num_user_formats;
>>
>> --
>> 2.25.1
>>

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