linux-kernel - Re: [PATCH v12,1/3] soc: mediatek: Add all settings to mtk_mmsys_ddp_dpi_fmt

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Date:   Thu, 20 Oct 2022 12:33:10 -0400
From:   Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
To:     xinlei.lee@...iatek.com
Cc:     matthias.bgg@...il.com, rex-bc.chen@...iatek.com,
        angelogioacchino.delregno@...labora.com, jason-jh.lin@...iatek.com,
        chunkuang.hu@...nel.org, p.zabel@...gutronix.de, airlied@...ux.ie,
        daniel@...ll.ch, dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v12,1/3] soc: mediatek: Add all settings to
 mtk_mmsys_ddp_dpi_fmt_config func

Hi,

On Wed, Oct 19, 2022 at 10:52:14AM +0800, xinlei.lee@...iatek.com wrote:
> From: Xinlei Lee <xinlei.lee@...iatek.com>
> 
> The difference between MT8186 and other ICs is that when modifying the
> output format, we need to modify the mmsys_base+0x400 register to take
> effect.
> So when setting the dpi output format, we need to call mmsys_func to set

mmsys_func isn't something that exists in the code. Instead mention the actual
function name: mtk_mmsys_ddp_dpi_fmt_config.

> it to MT8186 synchronously.


Here, before saying that the commit adds all the settings for dpi, you could
have mentioned that the previous commit lacked those, to make it clearer:

Commit a071e52f75d1 ("soc: mediatek: Add mmsys func to adapt to dpi output for MT8186")
lacked some of the possible output formats and also had a wrong bitmask.


> Adding mmsys all the settings that need to be modified with dpi are for
> mt8186.

This sentence I would change to the following one:

Add the missing output formats and fix the bitmask.


Finally, you're also making the function more HW-agnostic (although in my
opinion this could've been a future separate commit), so it's worth mentioning
it here:

While at it, also update mtk_mmsys_ddp_dpi_fmt_config() to use generic formats,
so that it is slightly easier to extend for other platforms.

> 
> Fixes: a071e52f75d1 ("soc: mediatek: Add mmsys func to adapt to dpi
> output for MT8186")

The fixes tag should be kept in a single line, without wrapping.

> 
> Signed-off-by: Xinlei Lee <xinlei.lee@...iatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> Reviewed-by: CK Hu <ck.hu@...iatek.com>
> ---
>  drivers/soc/mediatek/mt8186-mmsys.h    |  8 +++++---
>  drivers/soc/mediatek/mtk-mmsys.c       | 27 ++++++++++++++++++++------
>  include/linux/soc/mediatek/mtk-mmsys.h |  7 +++++++
>  3 files changed, 33 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/soc/mediatek/mt8186-mmsys.h b/drivers/soc/mediatek/mt8186-mmsys.h
> index 09b1ccbc0093..035aec1eb616 100644
> --- a/drivers/soc/mediatek/mt8186-mmsys.h
> +++ b/drivers/soc/mediatek/mt8186-mmsys.h
> @@ -5,9 +5,11 @@
>  
>  /* Values for DPI configuration in MMSYS address space */
>  #define MT8186_MMSYS_DPI_OUTPUT_FORMAT		0x400
> -#define DPI_FORMAT_MASK					0x1
> -#define DPI_RGB888_DDR_CON				BIT(0)
> -#define DPI_RGB565_SDR_CON				BIT(1)
> +#define DPI_FORMAT_MASK					GENMASK(1, 0)
> +#define DPI_RGB888_SDR_CON				0
> +#define DPI_RGB888_DDR_CON				1
> +#define DPI_RGB565_SDR_CON				2
> +#define DPI_RGB565_DDR_CON				3

These defines should all have a MT8186_ prefix. This will avoid confusions now
that mtk_mmsys_ddp_dpi_fmt_config() is being made more platform-agnostic.

>  
>  #define MT8186_MMSYS_OVL_CON			0xF04
>  #define MT8186_MMSYS_OVL0_CON_MASK			0x3
> diff --git a/drivers/soc/mediatek/mtk-mmsys.c b/drivers/soc/mediatek/mtk-mmsys.c
> index d2c7a87aab87..205f6de45851 100644
> --- a/drivers/soc/mediatek/mtk-mmsys.c
> +++ b/drivers/soc/mediatek/mtk-mmsys.c
> @@ -238,12 +238,27 @@ static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask,
>  
>  void mtk_mmsys_ddp_dpi_fmt_config(struct device *dev, u32 val)
>  {
> -	if (val)
> -		mtk_mmsys_update_bits(dev_get_drvdata(dev), MT8186_MMSYS_DPI_OUTPUT_FORMAT,
> -				      DPI_RGB888_DDR_CON, DPI_FORMAT_MASK);
> -	else
> -		mtk_mmsys_update_bits(dev_get_drvdata(dev), MT8186_MMSYS_DPI_OUTPUT_FORMAT,
> -				      DPI_RGB565_SDR_CON, DPI_FORMAT_MASK);
> +	struct mtk_mmsys *mmsys = dev_get_drvdata(dev);
> +
> +	switch (val) {
> +	case MTK_DPI_RGB888_SDR_CON:
> +		mtk_mmsys_update_bits(mmsys, MT8186_MMSYS_DPI_OUTPUT_FORMAT,
> +				      DPI_FORMAT_MASK, DPI_RGB888_SDR_CON);
> +		break;
> +	case MTK_DPI_RGB565_SDR_CON:
> +		mtk_mmsys_update_bits(mmsys, MT8186_MMSYS_DPI_OUTPUT_FORMAT,
> +				      DPI_FORMAT_MASK, DPI_RGB565_SDR_CON);
> +		break;
> +	case MTK_DPI_RGB565_DDR_CON:
> +		mtk_mmsys_update_bits(mmsys, MT8186_MMSYS_DPI_OUTPUT_FORMAT,
> +				      DPI_FORMAT_MASK, DPI_RGB565_DDR_CON);
> +		break;
> +	case MTK_DPI_RGB888_DDR_CON:
> +	default:
> +		mtk_mmsys_update_bits(mmsys, MT8186_MMSYS_DPI_OUTPUT_FORMAT,
> +				      DPI_FORMAT_MASK, DPI_RGB888_DDR_CON);
> +		break;
> +	}

To be honest I don't really see the point of making the function slightly more
platform-agnostic like this. With a single platform making use of it it's just
an unneeded extra abstraction, and it could easily be done when a second
platform starts requiring this as well...

In any case,

Reviewed-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>

Thanks,
Nícolas

>  }
[..]