RE: [PATCH] drm/stm: ltdc: check number of endpoints

From: Philippe CORNU
Date: Mon Mar 30 2020 - 09:40:32 EST


Dear Yannick,
Thank you for your patch,
Acked-by: Philippe Cornu <philippe.cornu@xxxxxx>
(sorry for the email format)
Philippe :-)

-----Original Message-----
From: Yannick FERTRE <yannick.fertre@xxxxxx>
Sent: Friday, February 28, 2020 09:08
To: Yannick FERTRE <yannick.fertre@xxxxxx>; Philippe CORNU <philippe.cornu@xxxxxx>; Benjamin GAIGNARD <benjamin.gaignard@xxxxxx>; David Airlie <airlied@xxxxxxxx>; Daniel Vetter <daniel@xxxxxxxx>; Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>; Alexandre TORGUE <alexandre.torgue@xxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: [PATCH] drm/stm: ltdc: check number of endpoints

Number of endpoints could exceed the fix value MAX_ENDPOINTS(2).
Instead of increase simply this value, the number of endpoint could be read from device tree. Load sequence has been a little rework to take care of several panel or bridge which can be connected/disconnected or enable/disable.

Signed-off-by: Yannick Fertre <yannick.fertre@xxxxxx>
---
drivers/gpu/drm/stm/ltdc.c | 102 +++++++++++++++++++++++----------------------
1 file changed, 52 insertions(+), 50 deletions(-)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c index df585fe..f894968 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -42,8 +42,6 @@

#define MAX_IRQ 4

-#define MAX_ENDPOINTS 2
-
#define HWVER_10200 0x010200
#define HWVER_10300 0x010300
#define HWVER_20101 0x020101
@@ -1201,36 +1199,20 @@ int ltdc_load(struct drm_device *ddev)
struct ltdc_device *ldev = ddev->dev_private;
struct device *dev = ddev->dev;
struct device_node *np = dev->of_node;
- struct drm_bridge *bridge[MAX_ENDPOINTS] = {NULL};
- struct drm_panel *panel[MAX_ENDPOINTS] = {NULL};
+ struct drm_bridge *bridge;
+ struct drm_panel *panel;
struct drm_crtc *crtc;
struct reset_control *rstc;
struct resource *res;
- int irq, ret, i, endpoint_not_ready = -ENODEV;
+ int irq, i, nb_endpoints;
+ int ret = -ENODEV;

DRM_DEBUG_DRIVER("\n");

- /* Get endpoints if any */
- for (i = 0; i < MAX_ENDPOINTS; i++) {
- ret = drm_of_find_panel_or_bridge(np, 0, i, &panel[i],
- &bridge[i]);
-
- /*
- * If at least one endpoint is -EPROBE_DEFER, defer probing,
- * else if at least one endpoint is ready, continue probing.
- */
- if (ret == -EPROBE_DEFER)
- return ret;
- else if (!ret)
- endpoint_not_ready = 0;
- }
-
- if (endpoint_not_ready)
- return endpoint_not_ready;
-
- rstc = devm_reset_control_get_exclusive(dev, NULL);
-
- mutex_init(&ldev->err_lock);
+ /* Get number of endpoints */
+ nb_endpoints = of_graph_get_endpoint_count(np);
+ if (!nb_endpoints)
+ return -ENODEV;

ldev->pixel_clk = devm_clk_get(dev, "lcd");
if (IS_ERR(ldev->pixel_clk)) {
@@ -1244,6 +1226,43 @@ int ltdc_load(struct drm_device *ddev)
return -ENODEV;
}

+ /* Get endpoints if any */
+ for (i = 0; i < nb_endpoints; i++) {
+ ret = drm_of_find_panel_or_bridge(np, 0, i, &panel, &bridge);
+
+ /*
+ * If at least one endpoint is -ENODEV, continue probing,
+ * else if at least one endpoint returned an error
+ * (ie -EPROBE_DEFER) then stop probing.
+ */
+ if (ret == -ENODEV)
+ continue;
+ else if (ret)
+ goto err;
+
+ if (panel) {
+ bridge = drm_panel_bridge_add_typed(panel,
+ DRM_MODE_CONNECTOR_DPI);
+ if (IS_ERR(bridge)) {
+ DRM_ERROR("panel-bridge endpoint %d\n", i);
+ ret = PTR_ERR(bridge);
+ goto err;
+ }
+ }
+
+ if (bridge) {
+ ret = ltdc_encoder_init(ddev, bridge);
+ if (ret) {
+ DRM_ERROR("init encoder endpoint %d\n", i);
+ goto err;
+ }
+ }
+ }
+
+ rstc = devm_reset_control_get_exclusive(dev, NULL);
+
+ mutex_init(&ldev->err_lock);
+
if (!IS_ERR(rstc)) {
reset_control_assert(rstc);
usleep_range(10, 20);
@@ -1285,27 +1304,7 @@ int ltdc_load(struct drm_device *ddev)
DRM_ERROR("Failed to register LTDC interrupt\n");
goto err;
}
- }

- /* Add endpoints panels or bridges if any */
- for (i = 0; i < MAX_ENDPOINTS; i++) {
- if (panel[i]) {
- bridge[i] = drm_panel_bridge_add_typed(panel[i],
- DRM_MODE_CONNECTOR_DPI);
- if (IS_ERR(bridge[i])) {
- DRM_ERROR("panel-bridge endpoint %d\n", i);
- ret = PTR_ERR(bridge[i]);
- goto err;
- }
- }
-
- if (bridge[i]) {
- ret = ltdc_encoder_init(ddev, bridge[i]);
- if (ret) {
- DRM_ERROR("init encoder endpoint %d\n", i);
- goto err;
- }
- }
}

crtc = devm_kzalloc(dev, sizeof(*crtc), GFP_KERNEL); @@ -1340,8 +1339,8 @@ int ltdc_load(struct drm_device *ddev)

return 0;
err:
- for (i = 0; i < MAX_ENDPOINTS; i++)
- drm_panel_bridge_remove(bridge[i]);
+ for (i = 0; i < nb_endpoints; i++)
+ drm_of_panel_bridge_remove(ddev->dev->of_node, 0, i);

clk_disable_unprepare(ldev->pixel_clk);

@@ -1350,11 +1349,14 @@ int ltdc_load(struct drm_device *ddev)

void ltdc_unload(struct drm_device *ddev) {
- int i;
+ struct device *dev = ddev->dev;
+ int nb_endpoints, i;

DRM_DEBUG_DRIVER("\n");

- for (i = 0; i < MAX_ENDPOINTS; i++)
+ nb_endpoints = of_graph_get_endpoint_count(dev->of_node);
+
+ for (i = 0; i < nb_endpoints; i++)
drm_of_panel_bridge_remove(ddev->dev->of_node, 0, i);

pm_runtime_disable(ddev->dev);
--
2.7.4