2021-08-09 07:27:39

by Derong Liu

Subject: [PATCH v2] mmc: mediatek: add wait dma stop done flow

We found this issue on a 5G platform, during CMDQ error handling, if DMA status is active when it call msdc_reset_hw, it means mmc host hw reset and DMA transfer will be parallel, mmc host may access sram region unexpectedly.

According to the programming guide of mtk mmc host,it needs to wait for dma stop done after set dma stop.
This change should be applied to all SoCs.

Signed-off-by: Derong Liu <[email protected]>
---
drivers/mmc/host/mtk-sd.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index 4dfc246c5f95..1dfd2842471b 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -2339,6 +2339,8 @@ static void msdc_cqe_disable(struct mmc_host *mmc, bool recovery)
if (recovery) {
sdr_set_field(host->base + MSDC_DMA_CTRL,
MSDC_DMA_CTRL_STOP, 1);
+ while (readl(host->base + MSDC_DMA_CFG) & MSDC_DMA_CFG_STS)
+ cpu_relax();
msdc_reset_hw(host);
}
}
--
2.18.0

2021-08-16 10:30:16

by Ulf Hansson

Subject: Re: [PATCH v2] mmc: mediatek: add wait dma stop done flow

On Mon, 9 Aug 2021 at 09:25, Derong Liu <[email protected]> wrote:
>
> We found this issue on a 5G platform, during CMDQ error handling, if DMA status is active when it call msdc_reset_hw, it means mmc host hw reset and DMA transfer will be parallel, mmc host may access sram region unexpectedly.
>
> According to the programming guide of mtk mmc host,it needs to wait for dma stop done after set dma stop.
> This change should be applied to all SoCs.
>
> Signed-off-by: Derong Liu <[email protected]>
> ---
> drivers/mmc/host/mtk-sd.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 4dfc246c5f95..1dfd2842471b 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -2339,6 +2339,8 @@ static void msdc_cqe_disable(struct mmc_host *mmc, bool recovery)
> if (recovery) {
> sdr_set_field(host->base + MSDC_DMA_CTRL,
> MSDC_DMA_CTRL_STOP, 1);
> + while (readl(host->base + MSDC_DMA_CFG) & MSDC_DMA_CFG_STS)
> + cpu_relax();

I suggest you look into using readl_poll_timeout() - as we don't want
to hang indefinitely, no matter what.

> msdc_reset_hw(host);
> }
> }
> --
> 2.18.0

Kind regards
Uffe