Re: [PATCH] drm/msm/adreno: fix gpu probe if no interconnect-names

On Wed, Jul 15, 2020 at 11:37 AM Jonathan Marek jonathan@marek.ca wrote:

On 7/15/20 2:29 PM, Rob Clark wrote:

...

From: Rob Clark robdclark@chromium.org

If there is no interconnect-names, but there is an interconnects property, then of_icc_get(dev, "gfx-mem"); would return an error rather than NULL.

Also, if there is no interconnect-names property, there will never be a ocmem path. But of_icc_get(dev, "ocmem") would return -EINVAL instead of -ENODATA. Just don't bother trying in this case.

Fixes: 8e29fb37b301 ("drm/msm: handle for EPROBE_DEFER for of_icc_get") Signed-off-by: Rob Clark robdclark@chromium.org

---

drivers/gpu/drm/msm/adreno/adreno_gpu.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c index 0527e85184e1..c4ac998b90c8 100644 --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c @@ -979,6 +979,7 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev, struct adreno_platform_config *config = dev->platform_data; struct msm_gpu_config adreno_gpu_config = { 0 }; struct msm_gpu *gpu = &adreno_gpu->base;

• bool has_interconnect_names = true;
  int ret;
  
  adreno_gpu->funcs = funcs;
  

@@ -1005,12 +1006,13 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,

  /* Check for an interconnect path for the bus */
  gpu->icc_path = of_icc_get(dev, "gfx-mem");

• if (!gpu->icc_path) {
  

• if (IS_ERR_OR_NULL(gpu->icc_path)) {
          /*
           * Keep compatbility with device trees that don't have an
           * interconnect-names property.
           */
          gpu->icc_path = of_icc_get(dev, NULL);
  

This is misleading because if it gets a EPROBE_DEFER error (or any other error), it will hit this path. Maybe there's a specific error you can check for instead to identify the "no-interconnect-names" case?

good point, we should probably instead just explicitly check with of_find_property("interconnect-names")

fwiw, of_icc_get() returns:

- NULL if icc disabled, or no "interconnects" property - -EINVAL if name!=NULL and no "interconnect-names" - and looks like -ENODATA if name!=NULL but no match in interconnect-names

The specific error returns aren't really called out in the API comment block, so not really sure how much we should rely on them not being implementation details.

BR, -R

Also don't think its a good idea to be calling of_icc_get(dev, NULL) again when there's a EPROBE_DEFER, the interconnect driver could come up between the two calls

...

•         has_interconnect_names = false;
  }
  if (IS_ERR(gpu->icc_path)) {
          ret = PTR_ERR(gpu->icc_path);
  

@@ -1018,7 +1020,9 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev, return ret; }

• gpu->ocmem_icc_path = of_icc_get(dev, "ocmem");
  

• if (has_interconnect_names)
  

•         gpu->ocmem_icc_path = of_icc_get(dev, "ocmem");
  

• if (IS_ERR(gpu->ocmem_icc_path)) {
          ret = PTR_ERR(gpu->ocmem_icc_path);
          gpu->ocmem_icc_path = NULL;