Patch "drm/tidss: Fix dss reset" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    drm/tidss: Fix dss reset

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-tidss-fix-dss-reset.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 ee7fd00e6fb3aae59f933335dfc8b953c74f6c4e
Author: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Date:   Thu Nov 9 09:38:01 2023 +0200

    drm/tidss: Fix dss reset
    
    [ Upstream commit bc288a927815efcf9d7f4a54d4d89c5df478c635 ]
    
    The probe function calls dispc_softreset() before runtime PM is enabled
    and without enabling any of the DSS clocks. This happens to work by
    luck, and we need to make sure the DSS HW is active and the fclk is
    enabled.
    
    To fix the above, add a new function, dispc_init_hw(), which does:
    
    - pm_runtime_set_active()
    - clk_prepare_enable(fclk)
    - dispc_softreset().
    
    This ensures that the reset can be successfully accomplished.
    
    Note that we use pm_runtime_set_active(), not the normal
    pm_runtime_get(). The reason for this is that at this point we haven't
    enabled the runtime PM yet and also we don't want the normal resume
    callback to be called: the dispc resume callback does some initial HW
    setup, and it expects that the HW was off (no video ports are
    streaming). If the bootloader has enabled the DSS and has set up a
    boot time splash-screen, the DSS would be enabled and streaming which
    might lead to issues with the normal resume callback.
    
    Fixes: c9b2d923befd ("drm/tidss: Soft Reset DISPC on startup")
    Reviewed-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
    Link: https://lore.kernel.org/r/20231109-tidss-probe-v2-8-ac91b5ea35c0@xxxxxxxxxxxxxxxx
    Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index 2af623842cfb..98efbaf3b0c2 100644
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -2724,6 +2724,49 @@ static int dispc_softreset(struct dispc_device *dispc)
 	return 0;
 }
 
+static int dispc_init_hw(struct dispc_device *dispc)
+{
+	struct device *dev = dispc->dev;
+	int ret;
+
+	ret = pm_runtime_set_active(dev);
+	if (ret) {
+		dev_err(dev, "Failed to set DSS PM to active\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(dispc->fclk);
+	if (ret) {
+		dev_err(dev, "Failed to enable DSS fclk\n");
+		goto err_runtime_suspend;
+	}
+
+	ret = dispc_softreset(dispc);
+	if (ret)
+		goto err_clk_disable;
+
+	clk_disable_unprepare(dispc->fclk);
+	ret = pm_runtime_set_suspended(dev);
+	if (ret) {
+		dev_err(dev, "Failed to set DSS PM to suspended\n");
+		return ret;
+	}
+
+	return 0;
+
+err_clk_disable:
+	clk_disable_unprepare(dispc->fclk);
+
+err_runtime_suspend:
+	ret = pm_runtime_set_suspended(dev);
+	if (ret) {
+		dev_err(dev, "Failed to set DSS PM to suspended\n");
+		return ret;
+	}
+
+	return ret;
+}
+
 int dispc_init(struct tidss_device *tidss)
 {
 	struct device *dev = tidss->dev;
@@ -2833,7 +2876,7 @@ int dispc_init(struct tidss_device *tidss)
 	of_property_read_u32(dispc->dev->of_node, "max-memory-bandwidth",
 			     &dispc->memory_bandwidth_limit);
 
-	r = dispc_softreset(dispc);
+	r = dispc_init_hw(dispc);
 	if (r)
 		return r;