Re: [PATCH v2 5/9] drm/panthor: Make getting GPU model name simple and extensible

Boris Brezillon
2025-03-21T08:03:00Z

On Thu, 20 Mar 2025 11:17:37 +0000
Karunika Choo <karunika.choo@arm.com> wrote:

> This patch replaces the previous 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 not only simplifies the comparison, but also allows extending the
> function to accommodate naming differences based on GPU features.
>
> Signed-off-by: Karunika Choo <karunika.choo@arm.com>
> ---
> drivers/gpu/drm/panthor/panthor_hw.c | 63 +++++++-------------------
> drivers/gpu/drm/panthor/panthor_regs.h | 1 +
> 2 files changed, 18 insertions(+), 46 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_hw.c b/drivers/gpu/drm/panthor/panthor_hw.c
> index 4cc4b0d5382c..12183c04cd21 100644
> --- a/drivers/gpu/drm/panthor/panthor_hw.c
> +++ b/drivers/gpu/drm/panthor/panthor_hw.c
> @@ -5,40 +5,6 @@
> #include "panthor_hw.h"
> #include "panthor_regs.h"
>
> -/**
> - * struct panthor_model - GPU model description
> - */
> -struct panthor_model {
> - /** @name: Model name. */
> - const char *name;
> -
> - /** @arch_major: Major version number of architecture. */
> - u8 arch_major;
> -
> - /** @product_major: Major version number of product. */
> - u8 product_major;
> -};
> -
> -/**
> - * GPU_MODEL() - Define a GPU model. A GPU product can be uniquely identified
> - * by a combination of the major architecture version and the major product
> - * version.
> - * @_name: Name for the GPU model.
> - * @_arch_major: Architecture major.
> - * @_product_major: Product major.
> - */
> -#define GPU_MODEL(_name, _arch_major, _product_major) \
> -{\
> - .name = __stringify(_name), \
> - .arch_major = _arch_major, \
> - .product_major = _product_major, \
> -}
> -
> -static const struct panthor_model gpu_models[] = {
> - GPU_MODEL(g610, 10, 7),
> - {},
> -};
> -
> static void arch_10_8_gpu_info_init(struct panthor_device *ptdev)
> {
> unsigned int i;
> @@ -66,29 +32,34 @@ static void arch_10_8_gpu_info_init(struct panthor_device *ptdev)
> ptdev->gpu_info.l2_present = gpu_read64(ptdev, GPU_L2_PRESENT_LO);
> }
>
> +static char *get_gpu_model_name(struct panthor_device *ptdev)
> +{
> + const u32 gpu_id = ptdev->gpu_info.gpu_id;
> + const u32 product_id = GPU_PROD_ID_MAKE(GPU_ARCH_MAJOR(gpu_id),
> + GPU_PROD_MAJOR(gpu_id));
> +
> + switch (product_id) {
> + case GPU_PROD_ID_MAKE(10, 7):
> + return "Mali-G610";
> + }

I a big fan of these ever growing switch statements with nested
conditionals. Could we instead add an optional ::get_variant() callback
in panthor_model and have the following formatting:

"Mali-%s%s%s", model->name,
model->get_variant ? "-" : "",
model->get_variant ? model->get_variant() : ""

> +
> + return "(Unknown Mali GPU)";
> +}
> +
> static void panthor_gpu_init_info(struct panthor_device *ptdev)
> {
> - const struct panthor_model *model;
> - u32 arch_major, product_major;
> + const char *gpu_model_name = get_gpu_model_name(ptdev);
> u32 major, minor, status;
>
> ptdev->hw->ops.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 ba452c1dd644..d9e0769d6f1a 100644
> --- a/drivers/gpu/drm/panthor/panthor_regs.h
> +++ b/drivers/gpu/drm/panthor/panthor_regs.h
> @@ -20,6 +20,7 @@
> #define GPU_VER_STATUS(x) ((x) & GENMASK(3, 0))
>
> #define GPU_ARCH_ID_MAKE(major, minor, rev) (((major) << 16) | ((minor) << 8) | (rev))
> +#define GPU_PROD_ID_MAKE(arch_major, prod_major) (((arch_major) << 24) | (prod_major))
>
> #define GPU_L2_FEATURES 0x4
> #define GPU_L2_FEATURES_LINE_SIZE(x) (1 << ((x) & GENMASK(7, 0)))