Re: [PATCH v3 03/12] drm/tyr: Set interconnect coherency during probe

[Boris Brezillon <boris.brezillon@collabora.com>]

On Mon, 23 Mar 2026 17:18:05 -0700
Deborah Brouwer <deborah.brouwer@collabora.com> wrote:

> Currently GpuInfo reports the interconnect coherency protocol as none
> without actually reading the `COHERENCY_ENABLE` register.
> 
> Although the result is the same, write `NO_COHERENCY` to the register
> during probe and then read back the register to populate the GpuInfo
> struct.
> 
> This ensures that GpuInfo is populated consistently and is always as
> accurate as possible by reporting the register values directly.
> 
> Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  drivers/gpu/drm/tyr/driver.rs | 5 +++++
>  drivers/gpu/drm/tyr/gpu.rs    | 2 +-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
> index 3ebb5e08bfca342f136e8d365b1d9dcb6cc3dbca..7232d9f9547c239689dc424380109a4e5140dd84 100644
> --- a/drivers/gpu/drm/tyr/driver.rs
> +++ b/drivers/gpu/drm/tyr/driver.rs
> @@ -136,6 +136,11 @@ fn probe(
>          issue_soft_reset(pdev.as_ref(), &iomem)?;
>          gpu::l2_power_on(pdev.as_ref(), &iomem)?;
>  
> +        let io = (*iomem).access(pdev.as_ref())?;
> +        // FIXME: This needs to be set properly once we get
> +        // device_get_dma_attr() properly exposed to the rust drivers.
> +        io.write_reg(COHERENCY_ENABLE::zeroed().with_l2_cache_protocol_select(CoherencyMode::None));
> +
>          let gpu_info = GpuInfo::new(pdev.as_ref(), &iomem)?;
>          gpu_info_log(pdev.as_ref(), &iomem)?;
>  
> diff --git a/drivers/gpu/drm/tyr/gpu.rs b/drivers/gpu/drm/tyr/gpu.rs
> index 4a50055b415c693a89cb99dba241b21351a14149..d5240f4567ca4e763b09e015908bdc5c22276e0d 100644
> --- a/drivers/gpu/drm/tyr/gpu.rs
> +++ b/drivers/gpu/drm/tyr/gpu.rs
> @@ -60,7 +60,7 @@ pub(crate) fn new(dev: &Device<Bound>, iomem: &Devres<IoMem>) -> Result<Self> {
>                  io.read(TEXTURE_FEATURES::at(3)).supported_formats().get(),
>              ],
>              as_present: io.read(AS_PRESENT).into_raw(),
> -            selected_coherency: uapi::drm_panthor_gpu_coherency_DRM_PANTHOR_GPU_COHERENCY_NONE,
> +            selected_coherency: io.read(COHERENCY_ENABLE).into_raw(),
>              shader_present: io.read(SHADER_PRESENT).into_raw(),
>              l2_present: io.read(L2_PRESENT).into_raw(),
>              tiler_present: io.read(TILER_PRESENT).into_raw(),
>