Patch "drm/panfrost: Really power off GPU cores in panfrost_gpu_power_off()" has been added to the 6.6-stable tree

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This is a note to let you know that I've just added the patch titled

    drm/panfrost: Really power off GPU cores in panfrost_gpu_power_off()

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-panfrost-really-power-off-gpu-cores-in-panfrost_.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c6fba450f4dec69820157802fde0a2e7e9d54f88
Author: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Date:   Thu Nov 2 15:15:07 2023 +0100

    drm/panfrost: Really power off GPU cores in panfrost_gpu_power_off()
    
    [ Upstream commit 22aa1a209018dc2eca78745f7666db63637cd5dc ]
    
    The layout of the registers {TILER,SHADER,L2}_PWROFF_LO, used to request
    powering off cores, is the same as the {TILER,SHADER,L2}_PWRON_LO ones:
    this means that in order to request poweroff of cores, we are supposed
    to write a bitmask of cores that should be powered off!
    This means that the panfrost_gpu_power_off() function has always been
    doing nothing.
    
    Fix powering off the GPU by writing a bitmask of the cores to poweroff
    to the relevant PWROFF_LO registers and then check that the transition
    (from ON to OFF) has finished by polling the relevant PWRTRANS_LO
    registers.
    
    While at it, in order to avoid code duplication, move the core mask
    logic from panfrost_gpu_power_on() to a new panfrost_get_core_mask()
    function, used in both poweron and poweroff.
    
    Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
    Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
    Reviewed-by: Steven Price <steven.price@xxxxxxx>
    Signed-off-by: Steven Price <steven.price@xxxxxxx>
    Link: https://patchwork.freedesktop.org/patch/msgid/20231102141507.73481-1-angelogioacchino.delregno@xxxxxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
index d28b99732dde..e20619169fe1 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
@@ -321,28 +321,38 @@ static void panfrost_gpu_init_features(struct panfrost_device *pfdev)
 		 pfdev->features.shader_present, pfdev->features.l2_present);
 }
 
+static u64 panfrost_get_core_mask(struct panfrost_device *pfdev)
+{
+	u64 core_mask;
+
+	if (pfdev->features.l2_present == 1)
+		return U64_MAX;
+
+	/*
+	 * Only support one core group now.
+	 * ~(l2_present - 1) unsets all bits in l2_present except
+	 * the bottom bit. (l2_present - 2) has all the bits in
+	 * the first core group set. AND them together to generate
+	 * a mask of cores in the first core group.
+	 */
+	core_mask = ~(pfdev->features.l2_present - 1) &
+		     (pfdev->features.l2_present - 2);
+	dev_info_once(pfdev->dev, "using only 1st core group (%lu cores from %lu)\n",
+		      hweight64(core_mask),
+		      hweight64(pfdev->features.shader_present));
+
+	return core_mask;
+}
+
 void panfrost_gpu_power_on(struct panfrost_device *pfdev)
 {
 	int ret;
 	u32 val;
-	u64 core_mask = U64_MAX;
+	u64 core_mask;
 
 	panfrost_gpu_init_quirks(pfdev);
+	core_mask = panfrost_get_core_mask(pfdev);
 
-	if (pfdev->features.l2_present != 1) {
-		/*
-		 * Only support one core group now.
-		 * ~(l2_present - 1) unsets all bits in l2_present except
-		 * the bottom bit. (l2_present - 2) has all the bits in
-		 * the first core group set. AND them together to generate
-		 * a mask of cores in the first core group.
-		 */
-		core_mask = ~(pfdev->features.l2_present - 1) &
-			     (pfdev->features.l2_present - 2);
-		dev_info_once(pfdev->dev, "using only 1st core group (%lu cores from %lu)\n",
-			      hweight64(core_mask),
-			      hweight64(pfdev->features.shader_present));
-	}
 	gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present & core_mask);
 	ret = readl_relaxed_poll_timeout(pfdev->iomem + L2_READY_LO,
 		val, val == (pfdev->features.l2_present & core_mask),
@@ -367,9 +377,27 @@ void panfrost_gpu_power_on(struct panfrost_device *pfdev)
 
 void panfrost_gpu_power_off(struct panfrost_device *pfdev)
 {
-	gpu_write(pfdev, TILER_PWROFF_LO, 0);
-	gpu_write(pfdev, SHADER_PWROFF_LO, 0);
-	gpu_write(pfdev, L2_PWROFF_LO, 0);
+	u64 core_mask = panfrost_get_core_mask(pfdev);
+	int ret;
+	u32 val;
+
+	gpu_write(pfdev, SHADER_PWROFF_LO, pfdev->features.shader_present & core_mask);
+	ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_PWRTRANS_LO,
+					 val, !val, 1, 1000);
+	if (ret)
+		dev_err(pfdev->dev, "shader power transition timeout");
+
+	gpu_write(pfdev, TILER_PWROFF_LO, pfdev->features.tiler_present);
+	ret = readl_relaxed_poll_timeout(pfdev->iomem + TILER_PWRTRANS_LO,
+					 val, !val, 1, 1000);
+	if (ret)
+		dev_err(pfdev->dev, "tiler power transition timeout");
+
+	gpu_write(pfdev, L2_PWROFF_LO, pfdev->features.l2_present & core_mask);
+	ret = readl_poll_timeout(pfdev->iomem + L2_PWRTRANS_LO,
+				 val, !val, 0, 1000);
+	if (ret)
+		dev_err(pfdev->dev, "l2 power transition timeout");
 }
 
 int panfrost_gpu_init(struct panfrost_device *pfdev)




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