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Message-ID: <223a5636-d399-afc6-748a-06835e7bf54d@collabora.com>
Date:   Thu, 14 Sep 2023 12:32:57 +0200
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Subject: Re: [PATCH v10 11/16] drm/mediatek: gamma: Add support for 12-bit LUT
 and MT8195
Content-Language: en-US
To:     Chen-Yu Tsai <wenst@chromium.org>
Cc:     chunkuang.hu@kernel.org, p.zabel@pengutronix.de, airlied@gmail.com,
        daniel@ffwll.ch, matthias.bgg@gmail.com,
        dri-devel@lists.freedesktop.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, kernel@collabora.com,
        ehristev@collabora.com,
        "Jason-JH . Lin" <jason-jh.lin@mediatek.com>,
        Alexandre Mergnat <amergnat@baylibre.com>
References: <20230804072850.89365-1-angelogioacchino.delregno@collabora.com>
 <20230804072850.89365-12-angelogioacchino.delregno@collabora.com>
 <CAGXv+5Hw2QqRVCqxZ+P96uM4hcm3qSQESA8Kh5b6RyJDQLFqQQ@mail.gmail.com>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <CAGXv+5Hw2QqRVCqxZ+P96uM4hcm3qSQESA8Kh5b6RyJDQLFqQQ@mail.gmail.com>
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Il 15/08/23 09:57, Chen-Yu Tsai ha scritto:
> On Fri, Aug 4, 2023 at 3:29 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@collabora.com> wrote:
>>
>> Add support for 12-bit gamma lookup tables and introduce the first
>> user for it: MT8195.
>> While at it, also reorder the variables in mtk_gamma_set_common()
>> and rename `lut_base` to `lut0_base` to improve readability.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> Reviewed-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
>> Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
>> ---
>>   drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 74 +++++++++++++++++++----
>>   1 file changed, 62 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
>> index 3f1c6815ea5a..7d2f8042ace0 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
>> @@ -26,12 +26,20 @@
>>   #define DISP_GAMMA_SIZE_VSIZE                          GENMASK(12, 0)
>>   #define DISP_GAMMA_BANK                                0x0100
>>   #define DISP_GAMMA_BANK_BANK                           GENMASK(1, 0)
>> +#define DISP_GAMMA_BANK_DATA_MODE                      BIT(2)
>>   #define DISP_GAMMA_LUT                         0x0700
>> +#define DISP_GAMMA_LUT1                                0x0b00
>>
>> +/* For 10 bit LUT layout, R/G/B are in the same register */
>>   #define DISP_GAMMA_LUT_10BIT_R                 GENMASK(29, 20)
>>   #define DISP_GAMMA_LUT_10BIT_G                 GENMASK(19, 10)
>>   #define DISP_GAMMA_LUT_10BIT_B                 GENMASK(9, 0)
>>
>> +/* For 12 bit LUT layout, R/G are in LUT, B is in LUT1 */
>> +#define DISP_GAMMA_LUT_12BIT_R                 GENMASK(11, 0)
>> +#define DISP_GAMMA_LUT_12BIT_G                 GENMASK(23, 12)
>> +#define DISP_GAMMA_LUT_12BIT_B                 GENMASK(11, 0)
>> +
>>   #define LUT_10BIT_MASK                         0x03ff
>>   #define LUT_BITS_DEFAULT                       10
>>   #define LUT_SIZE_DEFAULT                       512
>> @@ -77,14 +85,30 @@ unsigned int mtk_gamma_get_lut_size(struct device *dev)
>>          return LUT_SIZE_DEFAULT;
>>   }
>>
>> +/*
>> + * SoCs supporting 12-bits LUTs are using a new register layout that does
>> + * always support (by HW) both 12-bits and 10-bits LUT but, on those, we
>> + * ignore the support for 10-bits in this driver and always use 12-bits.
>> + *
>> + * Summarizing:
>> + * - SoC HW support 9/10-bits LUT only
>> + *   - Old register layout
>> + *     - 10-bits LUT supported
>> + *     - 9-bits LUT not supported
>> + * - SoC HW support both 10/12bits LUT
>> + *   - New register layout
>> + *     - 12-bits LUT supported
>> + *     - 10-its LUT not supported
>> + */
>>   void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
>>   {
>>          struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
>> -       unsigned int i;
>> -       struct drm_color_lut *lut;
>> -       void __iomem *lut_base;
>> -       u32 cfg_val, lbank_val, word;
>> +       void __iomem *lut0_base = gamma->regs + DISP_GAMMA_LUT;
>> +       void __iomem *lut1_base = gamma->regs + DISP_GAMMA_LUT1;
>> +       u32 cfg_val, data_mode, lbank_val, word[2];
>>          int cur_bank, num_lut_banks;
>> +       struct drm_color_lut *lut;
>> +       unsigned int i;
>>
>>          /* If there's no gamma lut there's nothing to do here. */
>>          if (!state->gamma_lut)
>> @@ -92,14 +116,17 @@ void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
>>
>>          num_lut_banks = gamma->data->lut_size / gamma->data->lut_bank_size;
>>          cfg_val = readl(gamma->regs + DISP_GAMMA_CFG);
>> -       lut_base = gamma->regs + DISP_GAMMA_LUT;
>>          lut = (struct drm_color_lut *)state->gamma_lut->data;
>>
>> +       /* Switch to 12 bits data mode if supported */
>> +       data_mode = FIELD_PREP(DISP_GAMMA_BANK_DATA_MODE, !!(gamma->data->lut_bits == 12));
>> +
>>          for (cur_bank = 0; cur_bank < num_lut_banks; cur_bank++) {
>>
>>                  /* Switch gamma bank and set data mode before writing LUT */
>>                  if (num_lut_banks > 1) {
>>                          lbank_val = FIELD_PREP(DISP_GAMMA_BANK_BANK, cur_bank);
>> +                       lbank_val |= data_mode;
>>                          writel(lbank_val, gamma->regs + DISP_GAMMA_BANK);
>>                  }
>>
>> @@ -112,9 +139,15 @@ void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
>>                          hwlut.blue = drm_color_lut_extract(lut[n].blue, gamma->data->lut_bits);
>>
>>                          if (!gamma->data->lut_diff || (i % 2 == 0)) {
>> -                               word = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, hwlut.red);
>> -                               word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, hwlut.green);
>> -                               word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, hwlut.blue);
>> +                               if (gamma->data->lut_bits == 12) {
>> +                                       word[0] = FIELD_PREP(DISP_GAMMA_LUT_12BIT_R, hwlut.red);
>> +                                       word[0] |= FIELD_PREP(DISP_GAMMA_LUT_12BIT_G, hwlut.green);
>> +                                       word[1] = FIELD_PREP(DISP_GAMMA_LUT_12BIT_B, hwlut.blue);
>> +                               } else {
>> +                                       word[0] = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, hwlut.red);
>> +                                       word[0] |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, hwlut.green);
>> +                                       word[0] |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, hwlut.blue);
>> +                               }
>>                          } else {
>>                                  diff.red = lut[n].red - lut[n - 1].red;
>>                                  diff.red = drm_color_lut_extract(diff.red, gamma->data->lut_bits);
>> @@ -125,11 +158,19 @@ void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
>>                                  diff.blue = lut[n].blue - lut[n - 1].blue;
>>                                  diff.blue = drm_color_lut_extract(diff.blue, gamma->data->lut_bits);
>>
>> -                               word = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, diff.red);
>> -                               word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, diff.green);
>> -                               word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, diff.blue);
>> +                               if (gamma->data->lut_bits == 12) {
>> +                                       word[0] = FIELD_PREP(DISP_GAMMA_LUT_12BIT_R, diff.red);
>> +                                       word[0] |= FIELD_PREP(DISP_GAMMA_LUT_12BIT_G, diff.green);
>> +                                       word[1] = FIELD_PREP(DISP_GAMMA_LUT_12BIT_B, diff.blue);
>> +                               } else {
>> +                                       word[0] = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, diff.red);
>> +                                       word[0] |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, diff.green);
>> +                                       word[0] |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, diff.blue);
>> +                               }
>>                          }
>> -                       writel(word, (lut_base + i * 4));
>> +                       writel(word[0], (lut0_base + i * 4));
>> +                       if (gamma->data->lut_bits == 12)
>> +                               writel(word[1], (lut1_base + i * 4));
>>                  }
>>          }
>>
>> @@ -246,11 +287,20 @@ static const struct mtk_disp_gamma_data mt8183_gamma_driver_data = {
>>          .lut_size = 512,
>>   };
>>
>> +static const struct mtk_disp_gamma_data mt8195_gamma_driver_data = {
>> +       .lut_bank_size = 256,
>> +       .lut_bits = 12,
>> +       .lut_diff = true,
>> +       .lut_size = 1024,
>> +};
>> +
>>   static const struct of_device_id mtk_disp_gamma_driver_dt_match[] = {
>>          { .compatible = "mediatek,mt8173-disp-gamma",
>>            .data = &mt8173_gamma_driver_data},
>>          { .compatible = "mediatek,mt8183-disp-gamma",
>>            .data = &mt8183_gamma_driver_data},
>> +       { .compatible = "mediatek,mt8195-disp-gamma",
>> +         .data = &mt8195_gamma_driver_data},
> 
> I assume we need matching changes for the DT binding and to the DT?
> 

Sorry for the late reply; no, we don't need any bindings/dt changes for this,
as the bindings are matching the current devicetree node in mt8195.dtsi, and
the node has

compatible = "mediatek,mt8195-disp-gamma", "mediatek,mt8183-disp-gamma";

so, no devicetree and/or bindings modification is needed.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm64/boot/dts/mediatek/mt8195.dtsi?h=next-20230914#n2724

Regards,
Angelo

> ChenYu
> 
>>          {},
>>   };
>>   MODULE_DEVICE_TABLE(of, mtk_disp_gamma_driver_dt_match);
>> --
>> 2.41.0
>>