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Date:   Tue, 1 Mar 2022 08:25:38 +0100
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Subject: Re: [PATCH v2] soc: mediatek: mtk-infracfg: Disable ACP on MT8192
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To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
        linux-mediatek@lists.infradead.org
Cc:     Chun-Jie Chen <chun-jie.chen@mediatek.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Chen-Yu Tsai <wenst@chromium.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Nick Fan <Nick.Fan@mediatek.com>,
        Nicolas Boichat <drinkcat@chromium.org>,
        Stephen Boyd <sboyd@kernel.org>
References: <20220215184651.12168-1-alyssa.rosenzweig@collabora.com>
 <e93b12d6-5c7b-2ad6-47e5-c1311d95cba2@collabora.com>
From:   Matthias Brugger <matthias.bgg@gmail.com>
In-Reply-To: <e93b12d6-5c7b-2ad6-47e5-c1311d95cba2@collabora.com>
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Precedence: bulk

Hi all,

On 17/02/2022 11:40, AngeloGioacchino Del Regno wrote:
> Il 15/02/22 19:46, Alyssa Rosenzweig ha scritto:
>> MT8192 contains an experimental Accelerator Coherency Port
>> implementation, which does not work correctly but was unintentionally
>> enabled by default. For correct operation of the GPU, we must set a
>> chicken bit disabling ACP on MT8192.
>>
>> Adapted from the following downstream change to the out-of-tree, legacy
>> Mali GPU driver:
>>
>> https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2781271/5 
>>
>>
>> Note this change is required for both Panfrost and the legacy kernel
>> driver.
> 
> Hello Alyssa,
> the v2 note should not get inside the commit message, even though they should be
> on the patch to provide context.
> Look at the example...
> 

I think the most obvious would be to disable the ACP in the boot firmware. But 
as we can't control that, we will need to work around it. So:
Patch applied. I fixed the commit message by deleting the v2 note.

Thanks everybody for figuring out what to do about that.

Regards,
Matthias

>>
>> v2: Move the change from clk-mt8192.c to mtk-infracfg.c (Robin).
>> Although it does not make sense to add this platform-specific hack to
>> the GPU driver, it has nothing to do with clocks. We already have
>> mtk-infracfg.c to manage other infracfg bits; the ACP disable should
>> live there too.
>>
>> Co-developed-by: Robin Murphy <robin.murphy@arm.com>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
>> Cc: Nick Fan <Nick.Fan@mediatek.com>
>> Cc: Nicolas Boichat <drinkcat@chromium.org>
>> Cc: Chen-Yu Tsai <wenst@chromium.org>
>> Cc: Stephen Boyd <sboyd@kernel.org>
>> Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> ---
> 
> v2: Move the change from clk-mt8192.c to mtk-infracfg.c (Robin).
> 
> ^^^ put it here, after the "---" :)
> 
> Anyway,
> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> 
>>   drivers/soc/mediatek/mtk-infracfg.c   | 19 +++++++++++++++++++
>>   include/linux/soc/mediatek/infracfg.h |  3 +++
>>   2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/soc/mediatek/mtk-infracfg.c 
>> b/drivers/soc/mediatek/mtk-infracfg.c
>> index 0590b68e0d78..2acf19676af2 100644
>> --- a/drivers/soc/mediatek/mtk-infracfg.c
>> +++ b/drivers/soc/mediatek/mtk-infracfg.c
>> @@ -6,6 +6,7 @@
>>   #include <linux/export.h>
>>   #include <linux/jiffies.h>
>>   #include <linux/regmap.h>
>> +#include <linux/mfd/syscon.h>
>>   #include <linux/soc/mediatek/infracfg.h>
>>   #include <asm/processor.h>
>> @@ -72,3 +73,21 @@ int mtk_infracfg_clear_bus_protection(struct regmap 
>> *infracfg, u32 mask,
>>       return ret;
>>   }
>> +
>> +static int __init mtk_infracfg_init(void)
>> +{
>> +    struct regmap *infracfg;
>> +
>> +    /*
>> +     * MT8192 has an experimental path to route GPU traffic to the DSU's
>> +     * Accelerator Coherency Port, which is inadvertently enabled by
>> +     * default. It turns out not to work, so disable it to prevent spurious
>> +     * GPU faults.
>> +     */
>> +    infracfg = syscon_regmap_lookup_by_compatible("mediatek,mt8192-infracfg");
>> +    if (!IS_ERR(infracfg))
>> +        regmap_set_bits(infracfg, MT8192_INFRA_CTRL,
>> +                MT8192_INFRA_CTRL_DISABLE_MFG2ACP);
>> +    return 0;
>> +}
>> +postcore_initcall(mtk_infracfg_init);
>> diff --git a/include/linux/soc/mediatek/infracfg.h 
>> b/include/linux/soc/mediatek/infracfg.h
>> index d858e0bab7a2..fcbbd0dd5e55 100644
>> --- a/include/linux/soc/mediatek/infracfg.h
>> +++ b/include/linux/soc/mediatek/infracfg.h
>> @@ -229,6 +229,9 @@
>>   #define INFRA_TOPAXI_PROTECTEN_SET        0x0260
>>   #define INFRA_TOPAXI_PROTECTEN_CLR        0x0264
>> +#define MT8192_INFRA_CTRL            0x290
>> +#define MT8192_INFRA_CTRL_DISABLE_MFG2ACP    BIT(9)
>> +
>>   #define REG_INFRA_MISC                0xf00
>>   #define F_DDR_4GB_SUPPORT_EN            BIT(13)
> 
>