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Message-ID: <20210326110706.qcu5ptxqeem3stot@uno.localdomain>
Date: Fri, 26 Mar 2021 12:07:06 +0100
From: Jacopo Mondi <jacopo@...ndi.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Jacopo Mondi <jacopo+renesas@...ndi.org>,
kieran.bingham+renesas@...asonboard.com,
niklas.soderlund+renesas@...natech.se, geert@...ux-m68k.org,
Mauro Carvalho Chehab <mchehab@...nel.org>,
linux-media@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 13/19] media: i2c: rdacm21: Power up OV10640 before
OV490
Hi Laurent,
On Sat, Mar 20, 2021 at 06:14:43PM +0200, Laurent Pinchart wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> On Fri, Mar 19, 2021 at 05:41:42PM +0100, Jacopo Mondi wrote:
> > The current RDACM21 initialization routine powers up the
> > OV10640 image sensor after the OV490 ISP. The ISP is programmed with
> > a firmware loaded from an embedded EEPROM that (most probably) tries
>
> It's actually a serial flash, not an EEPROM.
>
> > to interact and program also the image sensor connected to the ISP.
> >
> > As described in commit ccb26c5742f5 ("media: i2c: rdacm21: Fix OV10640
>
> That commit ID won't be valid anymore once the patches get merged,
> unless they are pulled instead of cherry-picked, which is currently not
> done in the Linux media subsystem. I'd drop it an only mention the
> commit's subject.
>
> > powerup") the image sensor powerdown signal is kept high by an internal
> > pull up resistor and occasionally fails to startup correctly if the
> > powerdown line is not asserted explicitly. Failures in the OV10640
> > startup causes the OV490 firmware to fail to boot correctly resulting in
> > the camera module initialization to fail consequentially.
> >
> > Fix this by powering up the OV10640 image sensor before testing the
> > OV490 firmware boot completion, by splitting the ov10640_initialize()
> > function in an ov10640_power_up() one and an ov10640_check_id() one.
> >
> > Also make sure the OV10640 identification procedure gives enough time to
> > the image sensor to resume after the programming phase performed by the
> > OV490 firmware by repeating the ID read procedure,
>
> s/,/./
>
I'll rework
> >
> > This commit fixes a sporadic start-up error triggered by a failure to
> > detect the OV490 firmware boot completion:
> > rdacm21 8-0054: Timeout waiting for firmware boot
> >
> > Fixes: a59f853b3b4b ("media: i2c: Add driver for RDACM21 camera module")
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>
> > ---
> > drivers/media/i2c/rdacm21.c | 46 ++++++++++++++++++++++++++-----------
> > 1 file changed, 32 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
> > index 3f38c465b348..3763eb690d74 100644
> > --- a/drivers/media/i2c/rdacm21.c
> > +++ b/drivers/media/i2c/rdacm21.c
> > @@ -69,6 +69,7 @@
> > #define OV490_ISP_VSIZE_LOW 0x80820062
> > #define OV490_ISP_VSIZE_HIGH 0x80820063
> >
> > +#define OV10640_PID_TIMEOUT 20
> > #define OV10640_ID_HIGH 0xa6
> > #define OV10640_CHIP_ID 0x300a
> > #define OV10640_PIXEL_RATE 55000000
> > @@ -314,10 +315,8 @@ static int rdacm21_get_fmt(struct v4l2_subdev *sd,
> > return 0;
> > }
> >
> > -static int ov10640_initialize(struct rdacm21_device *dev)
> > +static void ov10640_power_up(struct rdacm21_device *dev)
> > {
> > - u8 val;
> > -
> > /* Enable GPIO0#0 (reset) and GPIO1#0 (pwdn) as output lines. */
> > ov490_write_reg(dev, OV490_GPIO_SEL0, OV490_GPIO0);
> > ov490_write_reg(dev, OV490_GPIO_SEL1, OV490_SPWDN0);
> > @@ -332,18 +331,35 @@ static int ov10640_initialize(struct rdacm21_device *dev)
> > usleep_range(1500, 3000);
> > ov490_write_reg(dev, OV490_GPIO_OUTPUT_VALUE0, OV490_GPIO0);
> > usleep_range(3000, 5000);
> > +}
> >
> > - /* Read OV10640 ID to test communications. */
> > - ov490_write_reg(dev, OV490_SCCB_SLAVE0_DIR, OV490_SCCB_SLAVE_READ);
> > - ov490_write_reg(dev, OV490_SCCB_SLAVE0_ADDR_HIGH, OV10640_CHIP_ID >> 8);
> > - ov490_write_reg(dev, OV490_SCCB_SLAVE0_ADDR_LOW, OV10640_CHIP_ID & 0xff);
> > -
> > - /* Trigger SCCB slave transaction and give it some time to complete. */
> > - ov490_write_reg(dev, OV490_HOST_CMD, OV490_HOST_CMD_TRIGGER);
> > - usleep_range(1000, 1500);
> > +static int ov10640_check_id(struct rdacm21_device *dev)
> > +{
> > + unsigned int i;
> > + u8 val;
> >
> > - ov490_read_reg(dev, OV490_SCCB_SLAVE0_DIR, &val);
> > - if (val != OV10640_ID_HIGH) {
> > + /* Read OV10640 ID to test communications. */
> > + for (i = 0; i < OV10640_PID_TIMEOUT; ++i) {
>
> OV10640_PID_TIMEOUT is used in this function only, I would have made it
> local.
>
I don't think a local variable is better. The timeout is a read-only
constant which is better defined as a macro than a variable.
> > + ov490_write_reg(dev, OV490_SCCB_SLAVE0_DIR,
> > + OV490_SCCB_SLAVE_READ);
> > + ov490_write_reg(dev, OV490_SCCB_SLAVE0_ADDR_HIGH,
> > + OV10640_CHIP_ID >> 8);
> > + ov490_write_reg(dev, OV490_SCCB_SLAVE0_ADDR_LOW,
> > + OV10640_CHIP_ID & 0xff);
> > +
> > + /*
> > + * Trigger SCCB slave transaction and give it some time
> > + * to complete.
> > + */
> > + ov490_write_reg(dev, OV490_HOST_CMD, OV490_HOST_CMD_TRIGGER);
> > + usleep_range(1000, 1500);
>
> It would make sense to create an ov490_sensor_read() function to
> encapsulate all this.
>
Maybe on top when we'll have more users
> It would also be nicer to poll an OV490 register instead of sleeping
> blindly. That likely requires the OV490 application note (referenced in
> the datasheet), which we don't have. It may be useful to try and get
> hold of that. I still feel there may be something a bit fishy, but way
> less than before.
>
> > +
> > + ov490_read_reg(dev, OV490_SCCB_SLAVE0_DIR, &val);
> > + if (val == OV10640_ID_HIGH)
> > + break;
> > + usleep_range(1000, 1500);
> > + }
>
> Blank line ?
>
There isn't one intentionally as the two blocks are tightly coupled.
> > + if (i == OV10640_PID_TIMEOUT) {
> > dev_err(dev->dev, "OV10640 ID mismatch: (0x%02x)\n", val);
> > return -ENODEV;
> > }
> > @@ -359,6 +375,8 @@ static int ov490_initialize(struct rdacm21_device *dev)
> > unsigned int i;
> > int ret;
> >
> > + ov10640_power_up(dev);
>
> On top of this series, error handling of OV490 writes would make sense.
>
Maybe on top, yes
Is there anything major I should do to get a tag here ?
Thanks
j
> > +
> > /*
> > * Read OV490 Id to test communications. Give it up to 40msec to
> > * exit from reset.
> > @@ -396,7 +414,7 @@ static int ov490_initialize(struct rdacm21_device *dev)
> > return -ENODEV;
> > }
> >
> > - ret = ov10640_initialize(dev);
> > + ret = ov10640_check_id(dev);
> > if (ret)
> > return ret;
> >
>
> --
> Regards,
>
> Laurent Pinchart
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