> -----Original Message-----
> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Sent: 2019年11月26日 19:58
> To: BOUGH CHEN <haibo.chen@xxxxxxx>; ulf.hansson@xxxxxxxxxx
> Cc: linux-mmc@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>
> Subject: Re: [PATCH 02/14] mmc: sdhci: clear DMA_SEL before sending tuning
> command for Standard tuning
>
> On 15/11/19 1:07 PM, haibo.chen@xxxxxxx wrote:
> > From: Haibo Chen <haibo.chen@xxxxxxx>
> >
> > Currently, when use standard tuning, driver default disable DMA just
> > before send tuning command. But on i.MX8 usdhc, this is not enough.
> > Need also clear DMA_SEL. If not, once the DMA_SEL select AMDA2 before,
> > even dma already disabled, when send tuning command, usdhc will still
> > prefetch the ADMA script from wrong DMA address, then we will see
> > IOMMU report some error which show lack of TLB mapping.
> >
> > Signed-off-by: Haibo Chen <haibo.chen@xxxxxxx>
> > ---
> > drivers/mmc/host/sdhci.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index
> > 68db86c1b4c9..1436cc9c5f82 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -2361,6 +2361,7 @@ void sdhci_send_tuning(struct sdhci_host *host,
> u32 opcode)
> > struct mmc_request mrq = {};
> > unsigned long flags;
> > u32 b = host->sdma_boundary;
> > + u8 ctrl;
> >
> > spin_lock_irqsave(&host->lock, flags);
> >
> > @@ -2388,6 +2389,17 @@ void sdhci_send_tuning(struct sdhci_host *host,
> u32 opcode)
> > */
> > sdhci_writew(host, SDHCI_TRNS_READ, SDHCI_TRANSFER_MODE);
> >
> > +
> > + /* DMA already disabled, so clear the DMA Select here.
> > + * Otherwise, if use ADMA2, even disable DMA, some
> > + * controllers like i.MX usdhc will still prefetch the
> > + * ADMA script when send tuning command, which will cause
> > + * IOMMU report lack of TLB mapping error
> > + */
> > + ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
> > + ctrl &= ~SDHCI_CTRL_DMA_MASK;
>
> Value zero is SDMA, so this does not look like a generic sdhci change. What
> about doing it in sdhci-esdhc-imx.c before executing tuning?
>
Okay, the value zero for i.mx usdhc means "No DMA or Simple DMA is selected", a little bit different with generic sdhci definition.
I will add this change in sdhci-esdhc-imx.c in V2 patch.
Thanks!
Haibo Chen
> > + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
> > +
> > sdhci_send_command(host, &cmd);
> >
> > host->cmd = NULL;
> >
