linux-kernel - Re: [PATCH v5 7/8] pwm: pwm-omap-dmtimer: Adapt driver to utilize dmtimer pdata ops

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20171219152140.GA22971@lenoch>
Date:   Tue, 19 Dec 2017 16:21:40 +0100
From:   Ladislav Michl <ladis@...ux-mips.org>
To:     Keerthy <j-keerthy@...com>
Cc:     daniel.lezcano@...aro.org, tony@...mide.com, aaro.koskinen@....fi,
        thierry.reding@...il.com, grygorii.strashko@...com,
        linux-omap@...r.kernel.org, robh+dt@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-pwm@...r.kernel.org,
        sebastian.reichel@...labora.co.uk, linux-kernel@...r.kernel.org,
        t-kristo@...com, linux@...linux.org.uk
Subject: Re: [PATCH v5 7/8] pwm: pwm-omap-dmtimer: Adapt driver to utilize
 dmtimer pdata ops

On Tue, Dec 19, 2017 at 01:55:48PM +0530, Keerthy wrote:
> On Tuesday 19 December 2017 10:28 AM, Keerthy wrote:
> > On Monday 18 December 2017 06:25 PM, Keerthy wrote:
> >> On Monday 18 December 2017 03:01 PM, Ladislav Michl wrote:
> >>> Keerthy,
> >>>
> >>> On Tue, Dec 12, 2017 at 11:42:16AM +0530, Keerthy wrote:
> >>>> Adapt driver to utilize dmtimer pdata ops instead of pdata-quirks.
> >>>>
> >>>> Signed-off-by: Keerthy <j-keerthy@...com>
> >>>> ---
> >>>>
> >>>> Changes in v4:
> >>>>
> >>>>   * Switched to dev_get_platdata.
> >>>
> >>> Where do you expect dev.platform_data to be set? PWM driver is failing
> >>> with:
> >>> omap-dmtimer-pwm dmtimer-pwm: dmtimer pdata structure NULL
> >>> omap-dmtimer-pwm: probe of dmtimer-pwm failed with error -22
> >>>
> >>> Which I fixed with patch bellow, to be able to test your patchset.
> >>
> >> Thanks! I will make the below patch part of my series.
> >>
> >>>
> >>> Also I'm running a bit out of time, so I'll send few clean up
> >>> patches and event capture code to get some feedback early.
> >>>
> >>> Regards,
> >>> 	ladis
> >>>
> >>> diff --git a/drivers/clocksource/timer-dm.c b/drivers/clocksource/timer-dm.c
> >>> index 39be39e6a8dd..d3d8a49cae0d 100644
> >>> --- a/drivers/clocksource/timer-dm.c
> >>> +++ b/drivers/clocksource/timer-dm.c
> >>> @@ -773,6 +773,7 @@ static int omap_dm_timer_probe(struct platform_device *pdev)
> >>>  		dev_err(dev, "%s: no platform data.\n", __func__);
> >>>  		return -ENODEV;
> >>>  	}
> >>> +	dev->platform_data = pdata;
> > 
> > drivers/clocksource/timer-dm.c: In function 'omap_dm_timer_probe':
> > drivers/clocksource/timer-dm.c:744:21: warning: assignment discards
> > 'const' qualifier from pointer target type
> > 
> > This cannot be done as we are assigning a const pointer to a non-const
> > pointer.

Oh, I didn't even assume it as proper fix, just to show what is missing :)

But technically 'struct dmtimer_platform_data *pdata' is a constant which
should not be changed. Also look how all that of_populate chain works -
at the end const pointer is assigned to void* platform_data by simple
(void *) overcast.

> > I will figure out a different way for this fix.
> 
> Ladis,
> 
> I fixed that:
> 
> diff --git a/drivers/clocksource/timer-dm.c b/drivers/clocksource/timer-dm.c
> index 1cbd954..e58f555 100644
> --- a/drivers/clocksource/timer-dm.c
> +++ b/drivers/clocksource/timer-dm.c
> @@ -807,17 +807,21 @@ static int omap_dm_timer_probe(struct
> platform_device *pdev)
>         struct resource *mem, *irq;
>         struct device *dev = &pdev->dev;
>         const struct of_device_id *match;
> -       const struct dmtimer_platform_data *pdata;
> +       struct dmtimer_platform_data *pdata;
>         int ret;
> 
>         match = of_match_device(of_match_ptr(omap_timer_match), dev);
> -       pdata = match ? match->data : dev->platform_data;
> +       pdata = match ? (struct dmtimer_platform_data *)match->data :
> +               dev->platform_data;

All that seems needlesly complicated, what about patch bellow?

>         if (!pdata && !dev->of_node) {
>                 dev_err(dev, "%s: no platform data.\n", __func__);
>                 return -ENODEV;
>         }
> 
> +       if (!dev->platform_data)
> +               dev->platform_data = pdata;

Does the above condition bring us anything?

>         irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>         if (unlikely(!irq)) {
>                 dev_err(dev, "%s: no IRQ resource.\n", __func__);
> @@ -946,7 +950,7 @@ static int omap_dm_timer_remove(struct
> platform_device *pdev)
>         .write_status = omap_dm_timer_write_status,
>  };
> 
> -static const struct dmtimer_platform_data omap3plus_pdata = {
> +static struct dmtimer_platform_data omap3plus_pdata = {
>         .timer_errata = OMAP_TIMER_ERRATA_I103_I767,
>         .timer_ops = &dmtimer_ops,
>  };
> 
> Can you check at your end if this works for you?

Note, it is untested as I ran out of time and will continue after New Year.

diff --git a/drivers/clocksource/timer-dm.c b/drivers/clocksource/timer-dm.c
index 1cbd95420914..85024f11773a 100644
--- a/drivers/clocksource/timer-dm.c
+++ b/drivers/clocksource/timer-dm.c
@@ -806,14 +806,16 @@ static int omap_dm_timer_probe(struct platform_device *pdev)
 	struct omap_dm_timer *timer;
 	struct resource *mem, *irq;
 	struct device *dev = &pdev->dev;
-	const struct of_device_id *match;
 	const struct dmtimer_platform_data *pdata;
 	int ret;
 
-	match = of_match_device(of_match_ptr(omap_timer_match), dev);
-	pdata = match ? match->data : dev->platform_data;
+	pdata = of_device_get_match_data(dev);
+	if (!pdata)
+		pdata = dev_get_platdata(dev);
+	else
+		dev->platform_data = (void *) pdata;
 
-	if (!pdata && !dev->of_node) {
+	if (!pdata) {
 		dev_err(dev, "%s: no platform data.\n", __func__);
 		return -ENODEV;
 	}