[PATCH AUTOSEL 5.5 048/121] drm/sun4i: dsi: Use NULL to signify "no panel"

Sasha Levin
2020-04-11T23:38:18Z

From: Samuel Holland <samuel@sholland.org>

[ Upstream commit 0e4e3fb4901d19f49e5c0a582f383b10dda8d1c5 ]

The continued use of an ERR_PTR to signify "no panel" outside of
sun6i_dsi_attach is confusing because it is a double negative. Because
the connector always reports itself as connected, there is also the
possibility of sending an ERR_PTR to drm_panel_get_modes(), which would
crash.

Solve both of these by only storing the panel pointer if it is valid.

Fixes: 133add5b5ad4 ("drm/sun4i: Add Allwinner A31 MIPI-DSI controller support")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20200211072858.30784-2-samuel@sholland.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index c958ca9bae632..f1f9bcdfa372c 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -749,7 +749,7 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
phy_configure(dsi->dphy, &opts);
phy_power_on(dsi->dphy);

- if (!IS_ERR(dsi->panel))
+ if (dsi->panel)
drm_panel_prepare(dsi->panel);

/*
@@ -764,7 +764,7 @@ static void sun6i_dsi_encoder_enable(struct drm_encoder *encoder)
* ordering on the panels I've tested it with, so I guess this
* will do for now, until that IP is better understood.
*/
- if (!IS_ERR(dsi->panel))
+ if (dsi->panel)
drm_panel_enable(dsi->panel);

sun6i_dsi_start(dsi, DSI_START_HSC);
@@ -780,7 +780,7 @@ static void sun6i_dsi_encoder_disable(struct drm_encoder *encoder)

DRM_DEBUG_DRIVER("Disabling DSI output\n");

- if (!IS_ERR(dsi->panel)) {
+ if (dsi->panel) {
drm_panel_disable(dsi->panel);
drm_panel_unprepare(dsi->panel);
}
@@ -942,11 +942,13 @@ static int sun6i_dsi_attach(struct mipi_dsi_host *host,
struct mipi_dsi_device *device)
{
struct sun6i_dsi *dsi = host_to_sun6i_dsi(host);
+ struct drm_panel *panel = of_drm_find_panel(device->dev.of_node);

+ if (IS_ERR(panel))
+ return PTR_ERR(panel);
+
+ dsi->panel = panel;
dsi->device = device;
- dsi->panel = of_drm_find_panel(device->dev.of_node);
- if (IS_ERR(dsi->panel))
- return PTR_ERR(dsi->panel);

dev_info(host->dev, "Attached device %s\n", device->name);

--
2.20.1