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gpu: ipu-v3: prg: wait for double buffers to be filled on channel startup

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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>
This commit is contained in:
Lucas Stach 2017-03-24 18:01:53 +01:00 committed by Philipp Zabel
parent cda7755644
commit 263c3b8044
1 changed files with 7 additions and 0 deletions
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7
drivers/gpu/ipu-v3/ipu-prg.c
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@ -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;