Re: [PATCH v2 1/2] platform: make platform_get_irq_optional() optional

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Sergey,

On Sat, Feb 12, 2022 at 9:17 PM Sergey Shtylyov <s.shtylyov@xxxxxx> wrote:
> This patch is based on the former Andy Shevchenko's patch:
>
> https://lore.kernel.org/lkml/20210331144526.19439-1-andriy.shevchenko@xxxxxxxxxxxxxxx/
>
> Currently platform_get_irq_optional() returns an error code even if IRQ
> resource simply has not been found.  It prevents the callers from being
> error code agnostic in their error handling:
>
>         ret = platform_get_irq_optional(...);
>         if (ret < 0 && ret != -ENXIO)
>                 return ret; // respect deferred probe
>         if (ret > 0)
>                 ...we get an IRQ...
>
> All other *_optional() APIs seem to return 0 or NULL in case an optional
> resource is not available.  Let's follow this good example, so that the
> callers would look like:
>
>         ret = platform_get_irq_optional(...);
>         if (ret < 0)
>                 return ret;
>         if (ret > 0)
>                 ...we get an IRQ...
>
> Reported-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
> Signed-off-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
> ---
> Changes in version 2:

Thanks for the update!

>  drivers/base/platform.c                  | 60 +++++++++++++++---------

The core change LGTM.

I'm only looking at Renesas drivers below...

> --- a/drivers/mmc/host/sh_mmcif.c
> +++ b/drivers/mmc/host/sh_mmcif.c
> @@ -1465,14 +1465,14 @@ static int sh_mmcif_probe(struct platform_device *pdev)
>         sh_mmcif_sync_reset(host);
>         sh_mmcif_writel(host->addr, MMCIF_CE_INT_MASK, MASK_ALL);
>
> -       name = irq[1] < 0 ? dev_name(dev) : "sh_mmc:error";
> +       name = irq[1] <= 0 ? dev_name(dev) : "sh_mmc:error";

"== 0" should be sufficient here, if the code above would bail out
on errors returned by platform_get_irq_optional(), which it currently
doesn't do.
As this adds missing error handling, this is to be fixed by a separate
patch later?

>         ret = devm_request_threaded_irq(dev, irq[0], sh_mmcif_intr,
>                                         sh_mmcif_irqt, 0, name, host);
>         if (ret) {
>                 dev_err(dev, "request_irq error (%s)\n", name);
>                 goto err_clk;
>         }
> -       if (irq[1] >= 0) {
> +       if (irq[1] > 0) {

OK.

>                 ret = devm_request_threaded_irq(dev, irq[1],
>                                                 sh_mmcif_intr, sh_mmcif_irqt,
>                                                 0, "sh_mmc:int", host);

> --- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
> +++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
> @@ -439,7 +439,7 @@ static int rcar_gen3_phy_usb2_init(struct phy *p)
>         u32 val;
>         int ret;
>
> -       if (!rcar_gen3_is_any_rphy_initialized(channel) && channel->irq >= 0) {
> +       if (!rcar_gen3_is_any_rphy_initialized(channel) && channel->irq > 0) {
>                 INIT_WORK(&channel->work, rcar_gen3_phy_usb2_work);
>                 ret = request_irq(channel->irq, rcar_gen3_phy_usb2_irq,
>                                   IRQF_SHARED, dev_name(channel->dev), channel);
> @@ -486,7 +486,7 @@ static int rcar_gen3_phy_usb2_exit(struct phy *p)
>                 val &= ~USB2_INT_ENABLE_UCOM_INTEN;
>         writel(val, usb2_base + USB2_INT_ENABLE);
>
> -       if (channel->irq >= 0 && !rcar_gen3_is_any_rphy_initialized(channel))
> +       if (channel->irq > 0 && !rcar_gen3_is_any_rphy_initialized(channel))
>                 free_irq(channel->irq, channel);
>
>         return 0;

LGTM, but note that all errors returned by platform_get_irq_optional()
are currently ignored, even real errors, which should be propagated
up.
As this adds missing error handling, this is to be fixed by a separate
patch later?

> --- a/drivers/thermal/rcar_gen3_thermal.c
> +++ b/drivers/thermal/rcar_gen3_thermal.c
> @@ -432,6 +432,8 @@ static int rcar_gen3_thermal_request_irqs(struct rcar_gen3_thermal_priv *priv,
>                 irq = platform_get_irq_optional(pdev, i);
>                 if (irq < 0)
>                         return irq;
> +               if (!irq)
> +                       return -ENXIO;

While correct, and preserving existing behavior, this looks strange
to me.  Probably this should return zero instead (i.e. the check
above should be changed to "<= 0"), and the caller should start caring
about and propagating up real errors.
As this adds missing error handling, this is to be fixed by a separate
patch later?

>
>                 irqname = devm_kasprintf(dev, GFP_KERNEL, "%s:ch%d",
>                                          dev_name(dev), i);
> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> index fb65dc601b23..328ab074fd89 100644

> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c

I think you missed

    #define SCIx_IRQ_IS_MUXED(port)                 \
            ((port)->irqs[SCIx_ERI_IRQ] ==  \
             (port)->irqs[SCIx_RXI_IRQ]) || \
            ((port)->irqs[SCIx_ERI_IRQ] &&  \
             ((port)->irqs[SCIx_RXI_IRQ] < 0))

above? The last condition should become "<= 0".

> @@ -1915,7 +1915,7 @@ static int sci_request_irq(struct sci_port *port)
>                          * Certain port types won't support all of the
>                          * available interrupt sources.
>                          */
> -                       if (unlikely(irq < 0))
> +                       if (unlikely(irq <= 0))
>                                 continue;
>                 }
>
> @@ -1963,7 +1963,7 @@ static void sci_free_irq(struct sci_port *port)
>                  * Certain port types won't support all of the available
>                  * interrupt sources.
>                  */
> -               if (unlikely(irq < 0))
> +               if (unlikely(irq <= 0))
>                         continue;
>
>                 /* Check if already freed (irq was muxed) */
> @@ -2875,7 +2875,7 @@ static int sci_init_single(struct platform_device *dev,
>         if (sci_port->irqs[0] < 0)
>                 return -ENXIO;
>
> -       if (sci_port->irqs[1] < 0)
> +       if (sci_port->irqs[1] <= 0)
>                 for (i = 1; i < ARRAY_SIZE(sci_port->irqs); i++)
>                         sci_port->irqs[i] = sci_port->irqs[0];
>

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