drm/msm/a6xx: Ensure CX collapse during gpu recovery

Because there could be transient votes from other drivers/tz/hyp which
may keep the cx gdsc enabled, we should poll until cx gdsc collapses.
We can use the reset framework to poll for cx gdsc collapse from gpucc
clk driver.

This feature requires support from the platform's gpucc driver.

Signed-off-by: Akhil P Oommen <[e-mail]>
Reviewed-by: Dmitry Baryshkov <[e-mail]>
Reviewed-by: Philipp Zabel <[e-mail]>
Patchwork: https://patchwork.freedesktop.org/patch/498397/
Link: https://lore.kernel.org/r/20220819015030.v5.5.I176567525af2b9439a7e485d0ca130528666a55c@changeid
Signed-off-by: Rob Clark <[e-mail]>

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

···
 
 #include <linux/bitfield.h>
 #include <linux/devfreq.h>
+#include <linux/reset.h>
 #include <linux/soc/qcom/llcc-qcom.h>
 
 #define GPU_PAS_ID 13
···
 
 	/* And the final one from recover worker */
 	pm_runtime_put_sync(&gpu->pdev->dev);
+
+	/* Call into gpucc driver to poll for cx gdsc collapse */
+	reset_control_reset(gpu->cx_collapse);
 
 	pm_runtime_use_autosuspend(&gpu->pdev->dev);
 

drivers/gpu/drm/msm/msm_gpu.c

···
 #include <generated/utsrelease.h>
 #include <linux/string_helpers.h>
 #include <linux/devcoredump.h>
+#include <linux/reset.h>
 #include <linux/sched/task.h>
 
 /*
···
 	DBG("gpu_cx: %p", gpu->gpu_cx);
 	if (IS_ERR(gpu->gpu_cx))
 		gpu->gpu_cx = NULL;
+
+	gpu->cx_collapse = devm_reset_control_get_optional_exclusive(&pdev->dev,
+			"cx_collapse");
 
 	gpu->pdev = pdev;
 	platform_set_drvdata(pdev, &gpu->adreno_smmu);

drivers/gpu/drm/msm/msm_gpu.h

···
 #include <linux/interconnect.h>
 #include <linux/pm_opp.h>
 #include <linux/regulator/consumer.h>
+#include <linux/reset.h>
 
 #include "msm_drv.h"
 #include "msm_fence.h"
···
 	bool hw_apriv;
 
 	struct thermal_cooling_device *cooling;
+
+	/* To poll for cx gdsc collapse during gpu recovery */
+	struct reset_control *cx_collapse;
 };
 
 static inline struct msm_gpu *dev_to_gpu(struct device *dev)