On Mon, Nov 02, 2020 at 09:02:25PM +0100, Marijn Suijten wrote:

nr_rings is reset to 1, but when this function is called for a second (and third!) time nr_rings > 1 is false, thus the else case is entered to set up a buffer for the RPTR shadow and consequently written to RB_RPTR_ADDR, hanging platforms without WHERE_AM_I firmware support.

Restructure the condition in such a way that shadow buffer setup only ever happens when has_whereami is true; otherwise preemption is only finalized when the number of ring buffers has not been reset to 1 yet.

Fixes: 8907afb476ac ("drm/msm: Allow a5xx to mark the RPTR shadow as privileged") Signed-off-by: Marijn Suijten marijn.suijten@somainline.org Tested-by: AngeloGioacchino Del Regno angelogioacchino.delregno@somainline.org

Way better. Thanks for doing this.

Reviewed-by: Jordan Crouse jcrouse@codeaurora.org

---

drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c index d6804a802355..9a202a7da131 100644 --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c @@ -755,12 +755,8 @@ static int a5xx_hw_init(struct msm_gpu *gpu) gpu_write(gpu, REG_A5XX_CP_RB_CNTL, MSM_GPU_RB_CNTL_DEFAULT | AXXX_CP_RB_CNTL_NO_UPDATE);

• /* Disable preemption if WHERE_AM_I isn't available */
• if (!a5xx_gpu->has_whereami && gpu->nr_rings > 1) {

• a5xx_preempt_fini(gpu);
  

• gpu->nr_rings = 1;
  

• } else {

• /* Create a privileged buffer for the RPTR shadow */
  

• /* Create a privileged buffer for the RPTR shadow */
• if (a5xx_gpu->has_whereami) { if (!a5xx_gpu->shadow_bo) { a5xx_gpu->shadow = msm_gem_kernel_new(gpu->dev, sizeof(u32) * gpu->nr_rings,

@@ -774,6 +770,10 @@ static int a5xx_hw_init(struct msm_gpu *gpu)

gpu_write64(gpu, REG_A5XX_CP_RB_RPTR_ADDR,
	REG_A5XX_CP_RB_RPTR_ADDR_HI, shadowptr(a5xx_gpu, gpu->rb[0]));

• } else if (gpu->nr_rings > 1) {

• /* Disable preemption if WHERE_AM_I isn't available */
  

• a5xx_preempt_fini(gpu);
  

• gpu->nr_rings = 1;
  

  }

  a5xx_preempt_hw_init(gpu);

-- 2.29.2