linux-kernel - Re: [PATCH v10] staging: fbtft: add tearing signal detect

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Date:   Thu, 28 Jan 2021 19:03:01 +0800
From:   carlis <zhangxuezhi3@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Kari Argillander <kari.argillander@...il.com>,
        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 v10] staging: fbtft: add tearing signal detect

On Thu, 28 Jan 2021 10:42:54 +0100
Geert Uytterhoeven <geert@...ux-m68k.org> wrote:

> Hi Kari,
> 
> On Thu, Jan 28, 2021 at 7:53 AM Kari Argillander
> <kari.argillander@...il.com> wrote:
> > On Thu, Jan 28, 2021 at 09:42:58AM +0800, carlis wrote:  
> > > On Thu, 28 Jan 2021 00:32:22 +0200
> > > Kari Argillander <kari.argillander@...il.com> wrote:  
> > > > >  #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 /* msecs */
> > > > > +static struct mutex te_mutex;/* mutex for set te gpio irq
> > > > > status */  
> > > >
> > > > Space after ;  
> > > hi, i have fix it in the patch v11  
> > > >  
> >
> > Yeah sorry. I accidentally review wrong patch. But mostly stuff are
> > still relevant.
> >  
> > > > > @@ -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);
> > > > > +         return rc;
> > > > > + }  
> > > >
> > > > You request with optinal and you still want to error out? We
> > > > could just continue and not care about that error. User will be
> > > > happier if device still works somehow.  
> 
> devm_gpiod_get_index_optional() returns NULL, not an error, if the
> GPIO is not found.  So if IS_ERR() is the right check.
> 
> And checks for -EPROBE_DEFER can be handled automatically
> by using dev_err_probe() instead of dev_err().
> 
hi, i fix it like below!?
	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_probe(par->info->device, rc, "Failed to request
	te gpio\n"); return rc;
	}
	if (par->gpio.te) {
		init_completion(&spi_panel_te);
		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"); return rc;
		}

		disable_irq_nosync(gpiod_to_irq(par->gpio.te));
	} else {
		dev_info(par->info->device, "%s:%d, TE gpio not
		specified\n", __func__, __LINE__);
	}


> > > You mean i just delete this dev_err print ?!
> > > like this:
> > >       par->gpio.te = devm_gpiod_get_index_optional(dev, "te",
> > > 0,GPIOD_IN);
> > >         if (IS_ERR(par->gpio.te))
> > >               return PTR_ERR(par->gpio.te);  
> >
> > Not exactly. I'm suggesting something like this.
> >
> > if (IS_ERR(par->gpio.te) == -EPROBE_DEFER) {
> >         return -EPROBE_DEFER;
> >
> > if (IS_ERR(par->gpio.te))
> >         par-gpio.te = NULL;
> >
> > This like beginning of your patch series but the difference is that
> > if EPROBE_DEFER then we will try again later. Any other error and
> > we will just ignore TE gpio. But this is up to you what you want to
> > do. To me this just seems place where this kind of logic can work.  
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

regards,
zhangxuezhi