[PATCH v3 2/4] drm/rockchip: dsi: Reconfigure hardware on resume()

[Brian Norris <briannorris@chromium.org>]

Since commit 43c2de1002d2, we perform most HW configuration in the
bind() function. This configuration may be lost on suspend/resume, so we
need to call it again. That may lead to errors like this after system
suspend/resume:

  dw-mipi-dsi-rockchip ff968000.mipi: failed to write command FIFO
  panel-kingdisplay-kd097d04 ff960000.mipi.0: failed write init cmds: -110

Tested on Acer Chromebook Tab 10 (RK3399 Gru-Scarlet).

Note that early mailing list versions of this driver borrowed Rockchip's
downstream/BSP solution, to do HW configuration in mode_set() (which
*is* called at the appropriate pre-enable() times), but that was
discarded along the way. I've avoided that still, because mode_set()
documentation doesn't suggest this kind of purpose as far as I can tell.

Fixes: 43c2de1002d2 ("drm/rockchip: dsi: move all lane config except LCDC mux to bind()")
Cc: <stable@vger.kernel.org>
Signed-off-by: Brian Norris <briannorris@chromium.org>
---

Changes in v3:
 - New patch, to fix related PM issue discovered after patch 1

 .../gpu/drm/rockchip/dw-mipi-dsi-rockchip.c   | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
index 45676b23c019..21c67343cc6c 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
@@ -268,6 +268,8 @@ struct dw_mipi_dsi_rockchip {
 	struct dw_mipi_dsi *dmd;
 	const struct rockchip_dw_dsi_chip_data *cdata;
 	struct dw_mipi_dsi_plat_data pdata;
+
+	bool dsi_bound;
 };
 
 struct dphy_pll_parameter_map {
@@ -964,6 +966,8 @@ static int dw_mipi_dsi_rockchip_bind(struct device *dev,
 		goto out_pm_runtime;
 	}
 
+	dsi->dsi_bound = true;
+
 	return 0;
 
 out_pm_runtime:
@@ -983,6 +987,8 @@ static void dw_mipi_dsi_rockchip_unbind(struct device *dev,
 	if (dsi->is_slave)
 		return;
 
+	dsi->dsi_bound = false;
+
 	dw_mipi_dsi_unbind(dsi->dmd);
 
 	clk_disable_unprepare(dsi->pllref_clk);
@@ -1277,6 +1283,36 @@ static const struct phy_ops dw_mipi_dsi_dphy_ops = {
 	.exit		= dw_mipi_dsi_dphy_exit,
 };
 
+static int __maybe_unused dw_mipi_dsi_rockchip_resume(struct device *dev)
+{
+	struct dw_mipi_dsi_rockchip *dsi = dev_get_drvdata(dev);
+	int ret;
+
+	/*
+	 * Re-configure DSI state, if we were previously initialized. We need
+	 * to do this before rockchip_drm_drv tries to re-enable() any panels.
+	 */
+	if (dsi->dsi_bound) {
+		ret = clk_prepare_enable(dsi->grf_clk);
+		if (ret) {
+			DRM_DEV_ERROR(dsi->dev, "Failed to enable grf_clk: %d\n", ret);
+			return ret;
+		}
+
+		dw_mipi_dsi_rockchip_config(dsi);
+		if (dsi->slave)
+			dw_mipi_dsi_rockchip_config(dsi->slave);
+
+		clk_disable_unprepare(dsi->grf_clk);
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops dw_mipi_dsi_rockchip_pm_ops = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(NULL, dw_mipi_dsi_rockchip_resume)
+};
+
 static int dw_mipi_dsi_rockchip_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -1594,6 +1630,7 @@ struct platform_driver dw_mipi_dsi_rockchip_driver = {
 	.remove		= dw_mipi_dsi_rockchip_remove,
 	.driver		= {
 		.of_match_table = dw_mipi_dsi_rockchip_dt_ids,
+		.pm	= &dw_mipi_dsi_rockchip_pm_ops,
 		.name	= "dw-mipi-dsi-rockchip",
 	},
 };
-- 
2.33.0.685.g46640cef36-goog