linux-kernel - Re: [Linux-stm32] [PATCH v3 3/5] ARM: dts: stm32: enable ltdc binding with ili9341 on stm32429-disco board

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Date:   Fri, 15 May 2020 09:34:15 +0000
From:   Benjamin GAIGNARD <benjamin.gaignard@...com>
To:     dillon min <dillon.minfei@...il.com>
CC:     Alexandre TORGUE <alexandre.torgue@...com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Daniel Vetter <daniel@...ll.ch>,
        Dave Airlie <airlied@...ux.ie>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "open list:DRM PANEL DRIVERS" <dri-devel@...ts.freedesktop.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        "Sam Ravnborg" <sam@...nborg.org>,
        Michael Turquette <mturquette@...libre.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [Linux-stm32] [PATCH v3 3/5] ARM: dts: stm32: enable ltdc binding
 with ili9341 on stm32429-disco board


On 5/15/20 11:24 AM, dillon min wrote:
> Hi Benjamin,
>
> thanks for reply.
>
> On Fri, May 15, 2020 at 4:31 PM Benjamin GAIGNARD
> <benjamin.gaignard@...com> wrote:
>>
>>
>> On 5/14/20 3:07 PM, dillon min wrote:
>>> Hi Alexandre,
>>>
>>> On Thu, May 14, 2020 at 8:53 PM Alexandre Torgue
>>> <alexandre.torgue@...com> wrote:
>>>>
>>>> On 5/14/20 10:24 AM, Linus Walleij wrote:
>>>>> On Tue, May 12, 2020 at 9:04 AM <dillon.minfei@...il.com> wrote:
>>>>>
>>>>>> From: dillon min <dillon.minfei@...il.com>
>>>>>>
>>>>>> Enable the ltdc & ili9341 on stm32429-disco board.
>>>>>>
>>>>>> Signed-off-by: dillon min <dillon.minfei@...il.com>
>>>>> This mostly looks good but...
>>>>>
>>>>>> +&spi5 {
>>>>>> +       status = "okay";
>>>>>> +       pinctrl-0 = <&spi5_pins>;
>>>>>> +       pinctrl-names = "default";
>>>>>> +       #address-cells = <1>;
>>>>>> +       #size-cells = <0>;
>>>>>> +       cs-gpios = <&gpioc 2 GPIO_ACTIVE_LOW>;
>>>>>> +       dmas = <&dma2 3 2 0x400 0x0>,
>>>>>> +              <&dma2 4 2 0x400 0x0>;
>>>>>> +       dma-names = "rx", "tx";
>>>>> These DMA assignments seem to be SoC things and should
>>>>> rather be in the DTS(I) file where &spi5 is defined, right?
>>>>> stm32f429.dtsi I suppose?
>>>> I agree with Linus, DMA have to be defined in SoC dtsi. And if a board
>>>> doesn't want to use it, we use the "delete-property".
>>> Yes, will move to Soc dtsi in next submits.
>>>
>>> i'm working on write a v4l2-m2m driver for dma2d of stm32 to support
>>> pixel conversion
>>> alpha blending between foreground and background graphics.
>>>
>>> as you know, some soc's engineer trying to add this function to drm system.
>>>
>>> do you know st's planning about soc's hardware accelerator driver on stm32mp?
>>> such as chrom-art, will add to drm subsystem via ioctl to access, or to v4l2,
>> On stm32mp we do not plan to use chrom-art in drm or v4l2 because it
>> does fit
>> with userland way of working. We use the GPU to do conversion, scaling,
>> blending
>> and composition in only one go.
>> As explain here [1] DRM subsytem it isn't a solution and v4l2-m2m isn't
>> used in any
>> mainline compositors like Weston or android surfaceflinger.
>>
>> Benjamin
>>
> After check stm32mp's datasheets, they don't have chrom-art ip inside. sorry for
> didn't check it yet.
>
> for stm32h7 series with chrom-art, jpeg hardware accelerator inside.
> does st has plan to
> setup a driver to support it ? i prefer v4l2-m2m should be easier to
> implement it.
> co work with dcmi, fbdev.
ST doesn't plan to create a driver for chrom-art because nothing in 
mainline
userland could use it.

Benjamin
>
> thanks.
>
> best regards.
>
> Dillon
>> [1]
>> https://www.phoronix.com/scan.php?page=news_item&px=Linux-DRM-No-2D-Accel-API
>>> thanks.
>>>
>>>>> It is likely the same no matter which device is using spi5.
>>>>>
>>>>> Yours,
>>>>> Linus Walleij
>>>>>
>>> _______________________________________________
>>> Linux-stm32 mailing list
>>> Linux-stm32@...md-mailman.stormreply.com
>>> https://st-md-mailman.stormreply.com/mailman/listinfo/linux-stm32

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