linux-kernel - RE: [EXT] Re: [PATCH] media: imx-jpeg: Leave a blank space before the configuration data

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Date:   Fri, 27 May 2022 09:52:48 +0000
From:   Ming Qian <ming.qian@....com>
To:     Tommaso Merciai <tommaso.merciai@...rulasolutions.com>
CC:     "mchehab@...nel.org" <mchehab@...nel.org>,
        "Mirela Rabulea (OSS)" <mirela.rabulea@....nxp.com>,
        "hverkuil-cisco@...all.nl" <hverkuil-cisco@...all.nl>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [EXT] Re: [PATCH] media: imx-jpeg: Leave a blank space before the
 configuration data

> From: Tommaso Merciai <tommaso.merciai@...rulasolutions.com>
> Sent: 2022年5月27日 17:38
> To: Ming Qian <ming.qian@....com>
> Cc: mchehab@...nel.org; Mirela Rabulea (OSS)
> <mirela.rabulea@....nxp.com>; hverkuil-cisco@...all.nl;
> shawnguo@...nel.org; s.hauer@...gutronix.de; kernel@...gutronix.de;
> festevam@...il.com; dl-linux-imx <linux-imx@....com>;
> linux-media@...r.kernel.org; linux-kernel@...r.kernel.org;
> devicetree@...r.kernel.org; linux-arm-kernel@...ts.infradead.org
> Subject: [EXT] Re: [PATCH] media: imx-jpeg: Leave a blank space before the
> configuration data
> 
> Caution: EXT Email
> 
> Hi Ming,
> I think have some comments on the code for this would be nice for the future
> 
> On Fri, May 27, 2022 at 03:54:35PM +0800, Ming Qian wrote:
> > There is a hardware bug that it will load the first 128 bytes of
> > configuration data twice, it will led to some configure error.
> > so shift the configuration data 128 bytes, and make the first 128
> > bytes all zero, then hardware will load the 128 zero twice,
> 
> From what I've understood you initialize cfg_stm with zeros then you start to
> write the configuration from 0x80 (128 bytes), avoiding the hw issue right?
> 

HI Tommaso,
    Yes, you're right, there is a hardware bug.
I want to write the configuration data from the offset 0x80,
And set the first 128 bytes to zero.
Then the hardware bug can be avoided.

Ming.


> > and ignore them as garbage.
> > then the configuration data can be loaded correctly
> >
> > Signed-off-by: Ming Qian <ming.qian@....com>
> > Reviewed-by: Mirela Rabulea <mirela.rabulea@....com>
> > ---
> >  drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> > b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> > index 734e1b65fbc7..ad4213e020f3 100644
> > --- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> > +++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> > @@ -519,6 +519,7 @@ static bool mxc_jpeg_alloc_slot_data(struct
> mxc_jpeg_dev *jpeg,
> >                                    GFP_ATOMIC);
> >       if (!cfg_stm)
> >               goto err;
> > +     memset(cfg_stm, 0, MXC_JPEG_MAX_CFG_STREAM);
> >       jpeg->slot_data[slot].cfg_stream_vaddr = cfg_stm;
> >
> >  skip_alloc:
> > @@ -755,7 +756,7 @@ static unsigned int mxc_jpeg_setup_cfg_stream(void
> *cfg_stream_vaddr,
> >                                             u32 fourcc,
> >                                             u16 w, u16 h)  {
> > -     unsigned int offset = 0;
> > +     unsigned int offset = 0x80;
> >       u8 *cfg = (u8 *)cfg_stream_vaddr;
> >       struct mxc_jpeg_sof *sof;
> >       struct mxc_jpeg_sos *sos;
> > --
> > 2.36.1
> >
> 
> Thanks,
> Tommaso
> 
> --
> Tommaso Merciai
> Embedded Linux Engineer
> tommaso.merciai@...rulasolutions.com
> __________________________________
> 
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