Re: [PATCH v7, 2/4] drm/mediatek: Separate poweron/poweroff from enable/disable and define new funcs

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Il 20/05/22 04:00, xinlei.lee@xxxxxxxxxxxx ha scritto:
From: Jitao Shi <jitao.shi@xxxxxxxxxxxx>

In order to match the changes of "Use the drm_panel_bridge API",
the poweron/poweroff of dsi is extracted from enable/disable and
defined as new funcs (atomic_pre_enable/atomic_post_disable).

Since dsi_poweron is moved from dsi_enable to pre_enable function, in
order to avoid poweron failure, the operation of dsi register fails to
cause bus hang. Therefore, the protection mechanism is added to the
dsi_enable function.

Fixes: 2dd8075d2185 ("drm/mediatek: mtk_dsi: Use the drm_panel_bridge API")

Signed-off-by: Jitao Shi <jitao.shi@xxxxxxxxxxxx>
Signed-off-by: Xinlei Lee <xinlei.lee@xxxxxxxxxxxx>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Reviewed-by: Rex-BC Chen <rex-bc.chen@xxxxxxxxxxxx>
Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>

Hello Xinlei, CK, maintainers:

This patch is breaking machines that are using a DSI->DisplayPort bridge (like
the ANX7625 chip), but that's not the main issue.

----> I have never given a Reviewed-by tag for this commit <----

It's true I've given my tag for an older version [1] of this one, which was *not*
using atomic_* callbacks and that one worked fine (which is why I gave you
my R-b tag for it).

You have changed commits in this series to use atomic_(pre_)enable callbacks
but kept my tag, which is seriously wrong - and even more, because it's actually
breaking display support for a generous number of Chromebooks upstream.


Please be careful next time and ask for a new review when you make substantial
changes to your commits.


Anyway, I have already sent a fix for this situation, please look at [2].

Regards,
Angelo

[1]: https://patchwork.kernel.org/project/linux-mediatek/patch/1649644308-8455-3-git-send-email-xinlei.lee@xxxxxxxxxxxx/

[2]: https://lore.kernel.org/lkml/20220721172727.14624-1-angelogioacchino.delregno@xxxxxxxxxxxxx/T/#u

---
  drivers/gpu/drm/mediatek/mtk_dsi.c | 53 +++++++++++++++++++-----------
  1 file changed, 34 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index f880136cec09..d9a6b928dba8 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -691,16 +691,6 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
  	if (--dsi->refcount != 0)
  		return;
- /*
-	 * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
-	 * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
-	 * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
-	 * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
-	 * after dsi is fully set.
-	 */
-	mtk_dsi_stop(dsi);
-
-	mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
  	mtk_dsi_reset_engine(dsi);
  	mtk_dsi_lane0_ulp_mode_enter(dsi);
  	mtk_dsi_clk_ulp_mode_enter(dsi);
@@ -715,17 +705,9 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
static void mtk_output_dsi_enable(struct mtk_dsi *dsi)
  {
-	int ret;
-
  	if (dsi->enabled)
  		return;
- ret = mtk_dsi_poweron(dsi);
-	if (ret < 0) {
-		DRM_ERROR("failed to power on dsi\n");
-		return;
-	}
-
  	mtk_dsi_set_mode(dsi);
  	mtk_dsi_clk_hs_mode(dsi, 1);
@@ -739,7 +721,16 @@ static void mtk_output_dsi_disable(struct mtk_dsi *dsi)
  	if (!dsi->enabled)
  		return;
- mtk_dsi_poweroff(dsi);
+	/*
+	 * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
+	 * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
+	 * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
+	 * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
+	 * after dsi is fully set.
+	 */
+	mtk_dsi_stop(dsi);
+
+	mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
dsi->enabled = false;
  }
@@ -776,13 +767,37 @@ static void mtk_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
  {
  	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
+ if (dsi->refcount == 0)
+		return;
+
  	mtk_output_dsi_enable(dsi);
  }
+static void mtk_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge,
+					     struct drm_bridge_state *old_bridge_state)
+{
+	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
+	int ret;
+
+	ret = mtk_dsi_poweron(dsi);
+	if (ret < 0)
+		DRM_ERROR("failed to power on dsi\n");
+}
+
+static void mtk_dsi_bridge_atomic_post_disable(struct drm_bridge *bridge,
+					       struct drm_bridge_state *old_bridge_state)
+{
+	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
+
+	mtk_dsi_poweroff(dsi);
+}
+
  static const struct drm_bridge_funcs mtk_dsi_bridge_funcs = {
  	.attach = mtk_dsi_bridge_attach,
  	.atomic_disable = mtk_dsi_bridge_atomic_disable,
  	.atomic_enable = mtk_dsi_bridge_atomic_enable,
+	.atomic_pre_enable = mtk_dsi_bridge_atomic_pre_enable,
+	.atomic_post_disable = mtk_dsi_bridge_atomic_post_disable,
  	.mode_set = mtk_dsi_bridge_mode_set,
  };



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