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Re: [PATCH 2/3] pwm: Add PWM driver for OMAP using dual-mode timers

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  Re: [PATCH 2/3] pwm: Add PWM driver for OMAP using dual-mode timers Thierry Reding <thierry.reding@gmail.com> - 2015-12-16 17:30 +0100
    Re: [PATCH 2/3] pwm: Add PWM driver for OMAP using dual-mode timers Neil Armstrong <narmstrong@baylibre.com> - 2015-12-17 15:10 +0100

#1293080 — Re: [PATCH 2/3] pwm: Add PWM driver for OMAP using dual-mode timers

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On Mon, Nov 02, 2015 at 12:14:21PM +0100, Neil Armstrong wrote:
> Adds support for using a OMAP dual-mode timer with PWM capability
> as a Linux PWM device. The driver controls the timer by using the
> dmtimer API.
> 
> Add a platform_data structure for each pwm-omap-dmtimer nodes containing
> the dmtimers functions in order to get driver not rely on platform
> specific functions.
> 
> Cc: Grant Erickson <marathon96@gmail.com>
> Cc: NeilBrown <neilb@suse.de>
> Cc: Joachim Eastwood <manabian@gmail.com>
> Suggested-by: Tony Lindgren <tony@atomide.com>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
>  .../devicetree/bindings/pwm/pwm-omap-dmtimer.txt   |  18 ++
>  drivers/pwm/Kconfig                                |   9 +
>  drivers/pwm/Makefile                               |   1 +
>  drivers/pwm/pwm-omap-dmtimer.c                     | 322 +++++++++++++++++++++
>  include/linux/platform_data/pwm_omap_dmtimer.h     |  69 +++++
>  5 files changed, 419 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-omap-dmtimer.txt
>  create mode 100644 drivers/pwm/pwm-omap-dmtimer.c
>  create mode 100644 include/linux/platform_data/pwm_omap_dmtimer.h

I've applied this with some coding style bikeshedding applied. Also I
think there's a timer leak in the probe function:

> diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
[...]
> +static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
> +{
[...]
> +	dm_timer = pdata->request_by_node(timer);
> +	if (!dm_timer)
> +		return -EPROBE_DEFER;

dm_timer holds the requested timer now.

> +
> +	omap = devm_kzalloc(&pdev->dev, sizeof(*omap), GFP_KERNEL);
> +	if (!omap)
> +		return -ENOMEM;

But it's not released when this allocation fails...

> +
> +	omap->pdata = pdata;
> +	omap->dm_timer = dm_timer;
> +	omap->dm_timer_pdev = of_find_device_by_node(timer);
> +	if (!omap->dm_timer_pdev) {
> +		dev_err(&pdev->dev, "Unable to find timer pdev\n");
> +		return -EINVAL;
> +	}

... nor when this lookup fails. I've taken the liberty of adding two
calls to omap->pdata->free(dm_timer) to these error paths.

Please take a look at what's in the pwm/for-next branch to see if it
still works correctly.

Thanks,
Thierry

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#1293920

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Hi Thierry,
On 12/16/2015 05:27 PM, Thierry Reding wrote:
> I've applied this with some coding style bikeshedding applied. Also I
> think there's a timer leak in the probe function:
Indeed, the coding style had some root for ameliorations ! Thanks !
I also missed this timer leak, thanks for the fix.
>
>> diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
> [...]
>> +static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
>> +{
> [...]
>> +	dm_timer = pdata->request_by_node(timer);
>> +	if (!dm_timer)
>> +		return -EPROBE_DEFER;
>
> dm_timer holds the requested timer now.
>
>> +
>> +	omap = devm_kzalloc(&pdev->dev, sizeof(*omap), GFP_KERNEL);
>> +	if (!omap)
>> +		return -ENOMEM;
>
> But it's not released when this allocation fails...
>
>> +
>> +	omap->pdata = pdata;
>> +	omap->dm_timer = dm_timer;
>> +	omap->dm_timer_pdev = of_find_device_by_node(timer);
>> +	if (!omap->dm_timer_pdev) {
>> +		dev_err(&pdev->dev, "Unable to find timer pdev\n");
>> +		return -EINVAL;
>> +	}
>
> ... nor when this lookup fails. I've taken the liberty of adding two
> calls to omap->pdata->free(dm_timer) to these error paths.
Perfect !

> Please take a look at what's in the pwm/for-next branch to see if it
> still works correctly.
I had a look against my original patch and it should be ok, I will still hook it up back
on the real HW in case we forgot something.

> Thanks,
> Thierry
>

Thanks !
Neil

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