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Date: Mon, 2 Nov 2020 21:02:25 +0100 From: Marijn Suijten <marijn.suijten@...ainline.org> To: robdclark@...il.com Cc: konrad.dybcio@...ainline.org, martin.botka@...ainline.org, phone-devel@...r.kernel.org, Marijn Suijten <marijn.suijten@...ainline.org>, AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>, Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>, Jordan Crouse <jcrouse@...eaurora.org>, Konrad Dybcio <konradybcio@...il.com>, AngeloGioacchino Del Regno <kholk11@...il.com>, Eric Anholt <eric@...olt.net>, linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org Subject: [PATCH] drm/msm: a5xx: Make preemption reset case reentrant 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@...ainline.org> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.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
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