linux-kernel - Re: [PATCH v4 3/7] drm/panthor: Simplify getting the GPU model name

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Message-ID: <db1f5919-6d94-4563-9158-922cfd9c636b@arm.com>
Date: Mon, 21 Jul 2025 12:33:24 +0100
From: Karunika Choo <karunika.choo@....com>
To: Chia-I Wu <olvaffe@...il.com>
Cc: dri-devel@...ts.freedesktop.org, nd@....com,
 Boris Brezillon <boris.brezillon@...labora.com>,
 Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/7] drm/panthor: Simplify getting the GPU model name

On 11/06/2025 00:32, Chia-I Wu wrote:
> On Mon, Jun 2, 2025 at 8:16 AM Karunika Choo <karunika.choo@....com> wrote:
>>
>> This patch replaces the panthor_model structure with a simple switch
>> case based on the product_id which is in the format of:
>>         ((arch_major << 24) | product_major)
>>
>> This simplifies comparison and allows extending of the function to
>> accommodate naming differences based on supported GPU features.
>>
>> Signed-off-by: Karunika Choo <karunika.choo@....com>
>> ---
>>  drivers/gpu/drm/panthor/panthor_hw.c   | 63 +++++++-------------------
>>  drivers/gpu/drm/panthor/panthor_regs.h |  2 +
>>  2 files changed, 19 insertions(+), 46 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/panthor/panthor_hw.c b/drivers/gpu/drm/panthor/panthor_hw.c
>> index 576cda231c1c..421f84fde7d0 100644
>> --- a/drivers/gpu/drm/panthor/panthor_hw.c
>> +++ b/drivers/gpu/drm/panthor/panthor_hw.c
> <snipped>
>>  static void panthor_hw_info_init(struct panthor_device *ptdev)
>>  {
>> -       const struct panthor_model *model;
>> -       u32 arch_major, product_major;
>> +       const char *gpu_model_name = get_gpu_model_name(ptdev);
> Move this to after panthor_gpu_info_init below.
> 
> We want to init gpu info before dumping it in general.  And in fact,
> get_gpu_model_name will depend on gpu_features/shader_present in a
> later patch so this is a real bug.
>>         u32 major, minor, status;
>>
>>         panthor_gpu_info_init(ptdev);
>>
>> -       arch_major = GPU_ARCH_MAJOR(ptdev->gpu_info.gpu_id);
>> -       product_major = GPU_PROD_MAJOR(ptdev->gpu_info.gpu_id);
>>         major = GPU_VER_MAJOR(ptdev->gpu_info.gpu_id);
>>         minor = GPU_VER_MINOR(ptdev->gpu_info.gpu_id);
>>         status = GPU_VER_STATUS(ptdev->gpu_info.gpu_id);
>>
>> -       for (model = gpu_models; model->name; model++) {
>> -               if (model->arch_major == arch_major &&
>> -                   model->product_major == product_major)
>> -                       break;
>> -       }
>> -
>>         drm_info(&ptdev->base,
>> -                "mali-%s id 0x%x major 0x%x minor 0x%x status 0x%x",
>> -                model->name ?: "unknown", ptdev->gpu_info.gpu_id >> 16,
>> +                "%s id 0x%x major 0x%x minor 0x%x status 0x%x",
>> +                gpu_model_name, ptdev->gpu_info.gpu_id >> 16,
>>                  major, minor, status);
>>
>>         drm_info(&ptdev->base,
>> diff --git a/drivers/gpu/drm/panthor/panthor_regs.h b/drivers/gpu/drm/panthor/panthor_regs.h
>> index 48bbfd40138c..e7a81686afdb 100644
>> --- a/drivers/gpu/drm/panthor/panthor_regs.h
>> +++ b/drivers/gpu/drm/panthor/panthor_regs.h
>> @@ -19,6 +19,8 @@
>>  #define   GPU_VER_MINOR(x)                             (((x) & GENMASK(11, 4)) >> 4)
>>  #define   GPU_VER_STATUS(x)                            ((x) & GENMASK(3, 0))
>>
>> +#define GPU_PROD_ID_MAKE(arch_major, prod_major)       (((arch_major) << 24) | (prod_major))
> This macro has no hw significance and is only used to decide the model
> conveniently.  It should be moved to panthor_hw.c.
>
>
I have addressed both points in PATCH 2/6 of v5
- https://lore.kernel.org/all/20250721111344.1610250-3-karunika.choo@arm.com/
 >>  #define GPU_L2_FEATURES                                        0x4
>>  #define  GPU_L2_FEATURES_LINE_SIZE(x)                  (1 << ((x) & GENMASK(7, 0)))
>>
>> --
>> 2.49.0
>>