On Thu, 24 Oct 2024 15:54:31 +0100
Akash Goel <akash.g...@arm.com> wrote:
> This commit fixes the potential misalignment between the value of device
> tree property "dma-coherent" and default value of COHERENCY_ENABLE
> register.
> Panthor driver didn't explicitly program the COHERENCY_ENABLE register
> with the desired coherency mode. The default value of COHERENCY_ENABLE
> register is implementation defined, so it may not be always aligned with
> the "dma-coherent" property value.
> The commit also checks the COHERENCY_FEATURES register to confirm that
> the coherency protocol is actually supported or not.
>
> Signed-off-by: Akash Goel <akash.g...@arm.com>
Reviewed-by: Boris Brezillon <boris.brezil...@collabora.com>
> ---
> drivers/gpu/drm/panthor/panthor_device.c | 22 +++++++++++++++++++++-
> drivers/gpu/drm/panthor/panthor_gpu.c | 9 +++++++++
> 2 files changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c
> b/drivers/gpu/drm/panthor/panthor_device.c
> index 4082c8f2951d..984615f4ed27 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -22,6 +22,24 @@
> #include "panthor_regs.h"
> #include "panthor_sched.h"
>
> +static int panthor_gpu_coherency_init(struct panthor_device *ptdev)
> +{
> + ptdev->coherent = device_get_dma_attr(ptdev->base.dev) ==
> DEV_DMA_COHERENT;
> +
> + if (!ptdev->coherent)
> + return 0;
> +
> + /* Check if the ACE-Lite coherency protocol is actually supported by
> the GPU.
> + * ACE protocol has never been supported for command stream frontend
> GPUs.
> + */
> + if ((gpu_read(ptdev, GPU_COHERENCY_FEATURES) &
> + GPU_COHERENCY_PROT_BIT(ACE_LITE)))
> + return 0;
> +
> + drm_err(&ptdev->base, "Coherency not supported by the device");
> + return -ENOTSUPP;
> +}
> +
> static int panthor_clk_init(struct panthor_device *ptdev)
> {
> ptdev->clks.core = devm_clk_get(ptdev->base.dev, NULL);
> @@ -156,7 +174,9 @@ int panthor_device_init(struct panthor_device *ptdev)
> struct page *p;
> int ret;
>
> - ptdev->coherent = device_get_dma_attr(ptdev->base.dev) ==
> DEV_DMA_COHERENT;
> + ret = panthor_gpu_coherency_init(ptdev);
> + if (ret)
> + return ret;
>
> init_completion(&ptdev->unplug.done);
> ret = drmm_mutex_init(&ptdev->base, &ptdev->unplug.lock);
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c
> b/drivers/gpu/drm/panthor/panthor_gpu.c
> index 5251d8764e7d..1e24f08a519a 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> @@ -77,6 +77,12 @@ static const struct panthor_model gpu_models[] = {
> GPU_IRQ_RESET_COMPLETED | \
> GPU_IRQ_CLEAN_CACHES_COMPLETED)
>
> +static void panthor_gpu_coherency_set(struct panthor_device *ptdev)
> +{
> + gpu_write(ptdev, GPU_COHERENCY_PROTOCOL,
> + ptdev->coherent ? GPU_COHERENCY_PROT_BIT(ACE_LITE) :
> GPU_COHERENCY_NONE);
> +}
> +
> static void panthor_gpu_init_info(struct panthor_device *ptdev)
> {
> const struct panthor_model *model;
> @@ -365,6 +371,9 @@ int panthor_gpu_l2_power_on(struct panthor_device *ptdev)
> hweight64(ptdev->gpu_info.shader_present));
> }
>
> + /* Set the desired coherency mode before the power up of L2 */
> + panthor_gpu_coherency_set(ptdev);
> +
> return panthor_gpu_power_on(ptdev, L2, 1, 20000);
> }
>
