linux-kernel - Re: [PATCH v9] staging: fbtft: add tearing signal detect

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Message-ID: <CAMuHMdV=dsLv0stGa8OThOYLz2xG0Gg7EOYuFcKBeu+T_wANuw@mail.gmail.com>
Date:   Wed, 27 Jan 2021 14:47:04 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Carlis <zhangxuezhi3@...il.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Colin King <colin.king@...onical.com>,
        oliver.graute@...oconnector.com, zhangxuezhi1@...ong.com,
        mh12gx2825@...il.com, Stefano Brivio <sbrivio@...hat.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        driverdevel <devel@...verdev.osuosl.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9] staging: fbtft: add tearing signal detect

Hi Carlis,

On Wed, Jan 27, 2021 at 2:03 PM Carlis <zhangxuezhi3@...il.com> wrote:
> From: zhangxuezhi <zhangxuezhi1@...ong.com>
>
> For st7789v ic,add tearing signal detect to avoid screen tearing
>
> Signed-off-by: zhangxuezhi <zhangxuezhi1@...ong.com>
> ---
> v9: change pr_* to dev_*

Thanks for the update!

> --- a/drivers/staging/fbtft/fb_st7789v.c
> +++ b/drivers/staging/fbtft/fb_st7789v.c
> @@ -9,9 +9,12 @@
>  #include <linux/delay.h>
>  #include <linux/init.h>
>  #include <linux/kernel.h>
> +#include <linux/mutex.h>
> +#include <linux/interrupt.h>
> +#include <linux/completion.h>
>  #include <linux/module.h>
>  #include <video/mipi_display.h>
> -
> +#include <linux/gpio/consumer.h>
>  #include "fbtft.h"
>
>  #define DRVNAME "fb_st7789v"
> @@ -66,6 +69,32 @@ enum st7789v_command {
>  #define MADCTL_MX BIT(6) /* bitmask for column address order */
>  #define MADCTL_MY BIT(7) /* bitmask for page address order */
>
> +#define SPI_PANEL_TE_TIMEOUT   400
> +static struct mutex te_mutex;/*mutex for tearing line*/
> +static struct completion spi_panel_te;
> +
> +static irqreturn_t spi_panel_te_handler(int irq, void *data)
> +{
> +       complete(&spi_panel_te);
> +       return IRQ_HANDLED;
> +}
> +
> +static void set_spi_panel_te_irq_status(struct fbtft_par *par, bool enable)
> +{
> +       static int te_irq_count;
> +
> +       mutex_lock(&te_mutex);
> +
> +       if (enable) {
> +               if (++te_irq_count == 1)
> +                       enable_irq(gpiod_to_irq(par->gpio.te));
> +       } else {
> +               if (--te_irq_count == 0)
> +                       disable_irq(gpiod_to_irq(par->gpio.te));
> +       }
> +       mutex_unlock(&te_mutex);
> +}
> +
>  /**
>   * init_display() - initialize the display controller
>   *
> @@ -82,6 +111,33 @@ enum st7789v_command {
>   */
>  static int init_display(struct fbtft_par *par)
>  {
> +       int rc;
> +       struct device *dev = par->info->device;
> +
> +       par->gpio.te = devm_gpiod_get_index_optional(dev, "te", 0, GPIOD_IN);
> +       if (IS_ERR(par->gpio.te)) {
> +               rc = PTR_ERR(par->gpio.te);
> +               dev_err(par->info->device, "Failed to request te gpio: %d\n", rc);

This also prints an error in case of -EPROBE_DEFER.
dev_err_probe()?

> +               return rc;
> +       }
> +       if (par->gpio.te) {
> +               init_completion(&spi_panel_te);
> +               mutex_init(&te_mutex);
> +               rc = devm_request_irq(dev,
> +                                     gpiod_to_irq(par->gpio.te),
> +                                    spi_panel_te_handler, IRQF_TRIGGER_RISING,
> +                                    "TE_GPIO", par);
> +               if (rc) {
> +                       dev_err(par->info->device, "TE request_irq failed.\n");
> +                       devm_gpiod_put(dev, par->gpio.te);

No need to call devm_gpiod_put() here, as it's managed automatically.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

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