On 20.05.2018 16:48, Dmitry Osipenko wrote:
> DMA requests must be blocked before resetting VDE HW, otherwise it is
> possible to get a memory corruption or a machine hang. Use the reset
> control provided by the Memory Controller to block DMA before resetting
> the VDE HW.
>
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
> drivers/staging/media/tegra-vde/tegra-vde.c | 42 +++++++++++++++++++--
> 1 file changed, 38 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/media/tegra-vde/tegra-vde.c b/drivers/staging/media/tegra-vde/tegra-vde.c
> index 90177a59b97c..6dd3bf4481be 100644
> --- a/drivers/staging/media/tegra-vde/tegra-vde.c
> +++ b/drivers/staging/media/tegra-vde/tegra-vde.c
> @@ -73,6 +73,7 @@ struct tegra_vde {
> struct mutex lock;
> struct miscdevice miscdev;
> struct reset_control *rst;
> + struct reset_control *rst_mc;
> struct gen_pool *iram_pool;
> struct completion decode_completion;
> struct clk *clk;
> @@ -850,9 +851,23 @@ static int tegra_vde_ioctl_decode_h264(struct tegra_vde *vde,
> * We rely on the VDE registers reset value, otherwise VDE
> * causes bus lockup.
> */
> + ret = reset_control_assert(vde->rst_mc);
> + if (ret) {
> + dev_err(dev, "DEC start: Failed to assert MC reset: %d\n",
> + ret);
> + goto put_runtime_pm;
> + }
> +
> ret = reset_control_reset(vde->rst);
> if (ret) {
> - dev_err(dev, "Failed to reset HW: %d\n", ret);
> + dev_err(dev, "DEC start: Failed to reset HW: %d\n", ret);
> + goto put_runtime_pm;
> + }
> +
> + ret = reset_control_deassert(vde->rst_mc);
> + if (ret) {
> + dev_err(dev, "DEC start: Failed to deassert MC reset: %d\n",
> + ret);
> goto put_runtime_pm;
> }
>
> @@ -880,9 +895,21 @@ static int tegra_vde_ioctl_decode_h264(struct tegra_vde *vde,
> ret = timeout;
> }
>
> - err = reset_control_assert(vde->rst);
> - if (err)
> - dev_err(dev, "Failed to assert HW reset: %d\n", err);
> + /*
> + * At first reset memory client to avoid resetting VDE HW in the
> + * middle of DMA which could result into memory corruption or hang
> + * the whole system.
> + */
> + err = reset_control_assert(vde->rst_mc);
> + if (!err) {
It occurred to me that there is no need to skip the HW reset if MC resetting
fails. I'll make V2 to change that.
> + err = reset_control_assert(vde->rst);
> + if (err)
> + dev_err(dev,
> + "DEC end: Failed to assert HW reset: %d\n",
> + err);
> + } else {
> + dev_err(dev, "DEC end: Failed to assert MC reset: %d\n", err);
> + }
>
> put_runtime_pm:
> pm_runtime_mark_last_busy(dev);
> @@ -1074,6 +1101,13 @@ static int tegra_vde_probe(struct platform_device *pdev)
> return err;
> }
>
> + vde->rst_mc = devm_reset_control_get_optional(dev, "mc");
> + if (IS_ERR(vde->rst_mc)) {
> + err = PTR_ERR(vde->rst_mc);
> + dev_err(dev, "Could not get MC reset %d\n", err);
> + return err;
> + }
> +
> irq = platform_get_irq_byname(pdev, "sync-token");
> if (irq < 0)
> return irq;
>
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