linux-kernel - Re: [PATCH v12] staging: fbtft: add tearing signal detect

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Message-ID: <CAHp75VcRxPVs0KHwaY8QZima489D2_hntuW0eUqdfK8HJ-gnKA@mail.gmail.com>
Date:   Thu, 28 Jan 2021 16:44:02 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Carlis <zhangxuezhi3@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Colin King <colin.king@...onical.com>,
        oliver.graute@...oconnector.com, zhangxuezhi1@...ong.com,
        Deepak R Varma <mh12gx2825@...il.com>,
        Stefano Brivio <sbrivio@...hat.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        "open list:FRAMEBUFFER LAYER" <linux-fbdev@...r.kernel.org>,
        "open list:STAGING SUBSYSTEM" <devel@...verdev.osuosl.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v12] staging: fbtft: add tearing signal detect

On Thu, Jan 28, 2021 at 4:33 PM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
> On Thu, Jan 28, 2021 at 2:58 PM Carlis <zhangxuezhi3@...il.com> wrote:

...

> Taking all together you probably need to create a helper and use it
> inside init_display(), like
>
> static int init_tearing_effect_line(struct fbtft_par *par)
> {
>   struct device *dev = par->info->device;
>   struct gpio_desc *te;
>   int irq, rc;
>
>   te = gpiod_get_optional(dev, "te", GPIOD_IN);
>   if (IS_ERR(te))
>            return dev_err_probe(dev, PTR_ERR(te), "Failed to request
> te GPIO\n");

Sorry, here I missed the following:

  /* Absence of TE IRQ is not critical */
  if (!te)
    return 0;

>   irq = gpiod_to_irq(te); // this value you have to save in the
> driver's (per device) data structure.
>
>   /* GPIO is locked as an IRQ, we may drop the reference */
>   gpiod_put(te);

...and here:

  if (irq < 0)
    return irq;

>   init_completion(&spi_panel_te); // should be in the (per device)
> data structure
>   rc = devm_request_irq(dev, irq,  spi_panel_te_handler,
> IRQF_TRIGGER_RISING, "TE_GPIO", par);
>   if (rc)
>                 return dev_err_probe(dev, rc, "TE IRQ request failed.\n");
>   disable_irq_nosync(irq);
>   return irq;
> }

-- 
With Best Regards,
Andy Shevchenko