Hi Geert
On Mon, Nov 08, 2021 at 11:45:58AM +0100, Geert Uytterhoeven wrote:
> Hi Jacopo,
>
> On Thu, Nov 4, 2021 at 12:10 PM Jacopo Mondi <jacopo+renesas@xxxxxxxxxx> wrote:
> > Valid pixel clock detection is performed by spinning on a register read
> > which if repeated too frequently might fail. As the error is not fatal
> > ignore it instead of bailing out to continue spinning until the timeout
> > completion.
> >
> > Also relax the time between bus transactions and slightly increase the
> > wait interval to mitigate the failure risk.
> >
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> > Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> > ---
> >
> > v1->v2:
> > - Do not continue but jump to a label to respect the sleep timout after a
> > failed read
>
> Thanks for the update!
>
> > --- a/drivers/media/i2c/max9271.c
> > +++ b/drivers/media/i2c/max9271.c
> > @@ -55,7 +55,7 @@ static int max9271_write(struct max9271_device *dev, u8 reg, u8 val)
> > /*
> > * max9271_pclk_detect() - Detect valid pixel clock from image sensor
> > *
> > - * Wait up to 10ms for a valid pixel clock.
> > + * Wait up to 15ms for a valid pixel clock.
> > *
> > * Returns 0 for success, < 0 for pixel clock not properly detected
> > */
> > @@ -64,15 +64,16 @@ static int max9271_pclk_detect(struct max9271_device *dev)
> > unsigned int i;
> > int ret;
> >
> > - for (i = 0; i < 100; i++) {
> > + for (i = 0; i < 10; i++) {
> > ret = max9271_read(dev, 0x15);
> > if (ret < 0)
> > - return ret;
> > + goto skip;
>
> Edgar Dijkstra: Go To Statement Considered Harmful?
>
Dijkstra would be very unpleased reading the kernel error path
handling implementations. But I got your point, we're not in a cleanup
path here =)
> >
> > if (ret & MAX9271_PCLKDET)
>
> "if (ret > 0 && (ret & MAX9271_PCLKDET))"?
>
Much better, thanks. I'll resend!
Thanks
j
> > return 0;
> >
> > - usleep_range(50, 100);
> > +skip:
> > + usleep_range(1000, 1500);
> > }
> >
> > dev_err(&dev->client->dev, "Unable to detect valid pixel clock\n");
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
