linux-kernel - Re: [PATCH v8 08/13] drm/mediatek: gamma: Support multi-bank gamma LUT

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Date:   Wed, 2 Aug 2023 10:30:53 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     CK Hu (胡俊光) <ck.hu@...iatek.com>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "wenst@...omium.org" <wenst@...omium.org>,
        Jason-JH Lin (林睿祥) 
        <Jason-JH.Lin@...iatek.com>,
        "kernel@...labora.com" <kernel@...labora.com>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "amergnat@...libre.com" <amergnat@...libre.com>,
        "airlied@...il.com" <airlied@...il.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "ehristev@...labora.com" <ehristev@...labora.com>
Subject: Re: [PATCH v8 08/13] drm/mediatek: gamma: Support multi-bank gamma
 LUT

Il 02/08/23 06:12, CK Hu (胡俊光) ha scritto:
> Hi, Angelo:
> 
> On Tue, 2023-08-01 at 13:58 +0200, AngeloGioacchino Del Regno wrote:
>> Newer Gamma IP have got multiple LUT banks: support specifying the
>> size of the LUT banks and handle bank-switching before programming
>> the LUT in mtk_gamma_set_common() in preparation for adding support
>> for MT8195 and newer SoCs.
>>
>> Suggested-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
>> [Angelo: Refactored original commit]
>> Signed-off-by: AngeloGioacchino Del Regno <
>> angelogioacchino.delregno@...labora.com>
>> Reviewed-by: Alexandre Mergnat <amergnat@...libre.com>
>> ---
>>   drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 73 +++++++++++++++----
>> ----
>>   1 file changed, 47 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
>> b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
>> index a6f7af1a9e8e..fb7c3650a9f7 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
>> @@ -24,6 +24,8 @@
>>   #define DISP_GAMMA_SIZE				0x0030
>>   #define DISP_GAMMA_SIZE_HSIZE				GENMASK
>> (28, 16)
>>   #define DISP_GAMMA_SIZE_VSIZE				GENMASK
>> (12, 0)
>> +#define DISP_GAMMA_BANK				0x0100
>> +#define DISP_GAMMA_BANK_BANK				GENMASK(1, 0)
>>   #define DISP_GAMMA_LUT				0x0700
>>   
>>   #define DISP_GAMMA_LUT_10BIT_R			GENMASK(29, 20)
>> @@ -32,10 +34,12 @@
>>   
>>   #define LUT_10BIT_MASK				0x03ff
>>   #define LUT_BITS_DEFAULT			10
>> +#define LUT_BANK_SIZE_DEFAULT			512
>>   
>>   struct mtk_disp_gamma_data {
>>   	bool has_dither;
>>   	bool lut_diff;
>> +	u16 lut_bank_size;
>>   	u16 lut_size;
>>   	u8 lut_bits;
>>   };
>> @@ -80,7 +84,9 @@ void mtk_gamma_set_common(struct device *dev, void
>> __iomem *regs,
>>   	void __iomem *lut_base;
>>   	bool lut_diff;
>>   	u8 lut_bits;
>> -	u32 cfg_val, word;
>> +	u16 lut_bank_size;
>> +	u32 cfg_val, lbank_val, word;
>> +	int cur_bank, num_lut_banks;
>>   
>>   	/* If there's no gamma lut there's nothing to do here. */
>>   	if (!state->gamma_lut)
>> @@ -91,41 +97,54 @@ void mtk_gamma_set_common(struct device *dev,
>> void __iomem *regs,
>>   
>>   	if (gamma && gamma->data) {
>>   		lut_diff = gamma->data->lut_diff;
>> +		lut_bank_size = gamma->data->lut_bank_size;
>>   		lut_bits = gamma->data->lut_bits;
>>   	} else {
>>   		lut_diff = false;
>> +		lut_bank_size = LUT_BANK_SIZE_DEFAULT;
> 
> LUT_BANK_SIZE_DEFAULT is only for AAL driver, so place it in AAL driver
> and pass it into this function.
> 

I completely dislike having a function taking too many parameters.

Since mtk_gamma_set() in DISP_GAMMA will anyway expand in the future to
support newer hardware, I'm thinking about just removing AAL support from
this function and duplicate the few (15 or something) lines of code in
mtk_disp_aal instead, so that we stop commonizing the mtk_gamma_set for
both DISP_AAL and DISP_GAMMA.

Any opinions on that?

Regards,
Angelo

> Regards,
> CK
>