From: Lucas Stach l.stach@pengutronix.de

Wait for both double buffer to be filled when first starting a channel. This makes channel startup a lot more reliable, probably because it allows the internal state machine to settle before the requests from the IPU are coming in.

Signed-off-by: Lucas Stach l.stach@pengutronix.de [p.zabel@pengutronix.de: rebased before switch to runtime PM] Signed-off-by: Philipp Zabel p.zabel@pengutronix.de --- drivers/gpu/ipu-v3/ipu-prg.c | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/ipu-v3/ipu-prg.c b/drivers/gpu/ipu-v3/ipu-prg.c index ecc9ea44dc50f..0013ca9f72c83 100644 --- a/drivers/gpu/ipu-v3/ipu-prg.c +++ b/drivers/gpu/ipu-v3/ipu-prg.c @@ -14,6 +14,7 @@ #include <drm/drm_fourcc.h> #include <linux/clk.h> #include <linux/err.h> +#include <linux/iopoll.h> #include <linux/mfd/syscon.h> #include <linux/mfd/syscon/imx6q-iomuxc-gpr.h> #include <linux/module.h> @@ -329,6 +330,12 @@ int ipu_prg_channel_configure(struct ipuv3_channel *ipu_chan, val = IPU_PRG_REG_UPDATE_REG_UPDATE; writel(val, prg->regs + IPU_PRG_REG_UPDATE);

+ /* wait for both double buffers to be filled */ + readl_poll_timeout(prg->regs + IPU_PRG_STATUS, val, + (val & IPU_PRG_STATUS_BUFFER0_READY(prg_chan)) && + (val & IPU_PRG_STATUS_BUFFER1_READY(prg_chan)), + 5, 1000); + clk_disable_unprepare(prg->clk_ipg);

chan->enabled = true;