From: Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
To: Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
Cc: thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
alexandre.torgue-qxv4g6HH51o@public.gmane.org,
benjamin.gaignard-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org,
mark.rutland-5wv7dgnIgG8@public.gmane.org,
linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org,
mcoquelin.stm32-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
benjamin.gaignard-qxv4g6HH51o@public.gmane.org,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-pwm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 4/8] mfd: stm32-timers: add support for dmas
Date: Tue, 23 Jan 2018 15:30:35 +0000 [thread overview]
Message-ID: <20180123153035.2rvhspe2m5ej57op@dell> (raw)
In-Reply-To: <e611b40f-bd37-aa2d-afd9-997b86d55441-qxv4g6HH51o@public.gmane.org>
On Tue, 23 Jan 2018, Fabrice Gasnier wrote:
> On 01/23/2018 02:32 PM, Lee Jones wrote:
> > On Tue, 16 Jan 2018, Fabrice Gasnier wrote:
> >
> >> STM32 Timers can support up to 7 dma requests:
> >> 4 channels, update, compare and trigger.
> >> Optionally request part, or all dmas from stm32-timers MFD core.
> >> Also, keep reference of device's bus address to allow child drivers to
> >> transfer data from/to device by using dma.
> >>
> >> Signed-off-by: Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
> >> ---
> >> drivers/mfd/stm32-timers.c | 37 ++++++++++++++++++++++++++++++++++++-
> >> include/linux/mfd/stm32-timers.h | 14 ++++++++++++++
> >> 2 files changed, 50 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/mfd/stm32-timers.c b/drivers/mfd/stm32-timers.c
> >> index a6675a4..372b51e 100644
> >> --- a/drivers/mfd/stm32-timers.c
> >> +++ b/drivers/mfd/stm32-timers.c
> >> @@ -29,6 +29,23 @@ static void stm32_timers_get_arr_size(struct stm32_timers *ddata)
> >> regmap_write(ddata->regmap, TIM_ARR, 0x0);
> >> }
> >>
> >> +static void stm32_timers_dma_probe(struct device *dev,
> >> + struct stm32_timers *ddata)
> >> +{
> >> + int i;
> >> + char name[4];
> >> +
> >> + for (i = STM32_TIMERS_DMA_CH1; i <= STM32_TIMERS_DMA_CH4; i++) {
> >> + snprintf(name, ARRAY_SIZE(name), "ch%1d", i + 1);
> >> + ddata->dmas[i] = dma_request_slave_channel(dev, name);
> >
> > And if any of them fail?
>
> Hi Lee,
>
> If some of these fails, reference will be NULL. It is checked in child
> driver (pwm for instance) at runtime. Support is being added as an
> option: pwm capture will simply be unavailable in this case (fail with
> error).
Can you place a simple one-line comment in here please. Or else
someone will come along and add error handling for you.
> >> + }
> >> + ddata->dmas[STM32_TIMERS_DMA_UP] = dma_request_slave_channel(dev, "up");
> >> + ddata->dmas[STM32_TIMERS_DMA_TRIG] =
> >> + dma_request_slave_channel(dev, "trig");
> >> + ddata->dmas[STM32_TIMERS_DMA_COM] =
> >> + dma_request_slave_channel(dev, "com");
> >
> > Can you format these in the same why. This hurts my eyes.
>
> I use enum values and try to match as possible with reference manual for
> "up", "trig" & "com" names.
> Would have some suggestion to beautify this?
I just mean, can you push the first dma_request_slave_channel() call
on to the next line, so each of the calls are formatted in the same
manner please?
> >> +}
> >> +
> >> static int stm32_timers_probe(struct platform_device *pdev)
> >> {
> >> struct device *dev = &pdev->dev;
> >> @@ -44,6 +61,7 @@ static int stm32_timers_probe(struct platform_device *pdev)
> >> mmio = devm_ioremap_resource(dev, res);
> >> if (IS_ERR(mmio))
> >> return PTR_ERR(mmio);
> >> + ddata->phys_base = res->start;
> >
> > What do you use this for?
>
> This is used in in child driver (pwm) for capture data transfer by dma.
Might be worth being clear about that.
Perhaps pass in 'dma_base' (phys_base + offset) instead?
--
Lee Jones
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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next prev parent reply other threads:[~2018-01-23 15:30 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-16 12:43 [PATCH 0/8] Add support for PWM input capture on STM32 Fabrice Gasnier
2018-01-16 12:43 ` [PATCH 1/8] pwm: stm32: fix, remove unused struct device Fabrice Gasnier
2018-01-16 12:43 ` [PATCH 2/8] pwm: stm32: protect common prescaler for all channels Fabrice Gasnier
2018-01-16 12:43 ` [PATCH 3/8] dt-bindings: mfd: stm32-timers: add support for dmas Fabrice Gasnier
2018-01-16 12:43 ` [PATCH 4/8] " Fabrice Gasnier
[not found] ` <1516106631-18722-5-git-send-email-fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
2018-01-23 13:32 ` Lee Jones
2018-01-23 13:57 ` Fabrice Gasnier
[not found] ` <e611b40f-bd37-aa2d-afd9-997b86d55441-qxv4g6HH51o@public.gmane.org>
2018-01-23 15:30 ` Lee Jones [this message]
2018-01-23 15:52 ` Fabrice Gasnier
[not found] ` <ee021839-3298-d01b-8890-619aca0399a7-qxv4g6HH51o@public.gmane.org>
2018-01-23 16:41 ` Lee Jones
2018-01-24 8:40 ` Fabrice Gasnier
2018-01-24 14:56 ` Lee Jones
2018-01-24 15:30 ` Fabrice Gasnier
2018-01-24 15:43 ` cas
2018-01-16 12:43 ` [PATCH 5/8] pwm: stm32: add capture support Fabrice Gasnier
2018-01-16 12:43 ` [PATCH 6/8] pwm: stm32: improve capture by tuning counter prescaler Fabrice Gasnier
[not found] ` <1516106631-18722-1-git-send-email-fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
2018-01-16 12:43 ` [PATCH 7/8] pwm: stm32: use input prescaler to improve period capture Fabrice Gasnier
2018-01-16 12:43 ` [PATCH 8/8] ARM: dts: stm32: Enable pwm3 input capture on stm32f429i-eval Fabrice Gasnier
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