linux-kernel - [PATCH v2] drm/msm/adreno: adreno_gpu: Use suspend() instead of idle() on load error

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Message-Id: <20230330231517.2747024-1-konrad.dybcio@linaro.org>
Date:   Fri, 31 Mar 2023 01:15:16 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     linux-arm-msm@...r.kernel.org, andersson@...nel.org,
        agross@...nel.org
Cc:     marijn.suijten@...ainline.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Johan Hovold <johan+linaro@...nel.org>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>,
        Nathan Chancellor <nathan@...nel.org>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] drm/msm/adreno: adreno_gpu: Use suspend() instead of idle() on load error

The adreno_load_gpu() path is guarded by an error check on
adreno_load_fw(). This function is responsible for loading
Qualcomm-only-signed binaries (e.g. SQE and GMU FW for A6XX), but it
does not take the vendor-signed ZAP blob into account.

By embedding the SQE (and GMU, if necessary) firmware into the
initrd/kernel, we can trigger and unfortunate path that would not bail
out early and proceed with gpu->hw_init(). That will fail, as the ZAP
loader path will not find the firmware and return back to
adreno_load_gpu().

This error path involves pm_runtime_put_sync() which then calls idle()
instead of suspend(). This is suboptimal, as it means that we're not
going through the clean shutdown sequence. With at least A619_holi, this
makes the GPU not wake up until it goes through at least one more
start-fail-stop cycle. The pm_runtime_put_sync that appears in the error
path actually does not guarantee that because of the earlier enabling of
runtime autosuspend.

Fix that by using pm_runtime_put_sync_suspend to force a clean shutdown.

Test cases:
1. All firmware baked into kernel
2. error loading ZAP fw in initrd -> load from rootfs at DE start

Both succeed on A619_holi (SM6375) and A630 (SDM845).

Fixes: 0d997f95b70f ("drm/msm/adreno: fix runtime PM imbalance at gpu load")
Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
---
v1 -> v2:
- Improve the commit message and the reasoning within

 drivers/gpu/drm/msm/adreno/adreno_device.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
index f61896629be6..59f3302e8167 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_device.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
@@ -477,7 +477,7 @@ struct msm_gpu *adreno_load_gpu(struct drm_device *dev)
 	return gpu;

 err_put_rpm:
-	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_put_sync_suspend(&pdev->dev);
 err_disable_rpm:
 	pm_runtime_disable(&pdev->dev);

-- 
2.40.0