> -----Original Message-----
> From: linux-mmc-owner@xxxxxxxxxxxxxxx <linux-mmc-owner@xxxxxxxxxxxxxxx>
> On Behalf Of Adrian Hunter
> Sent: 2019年11月26日 19:46
> To: BOUGH CHEN <haibo.chen@xxxxxxx>; ulf.hansson@xxxxxxxxxx
> Cc: linux-mmc@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>
> Subject: Re: [PATCH 03/14] mmc: sdhci: correct the DMA setting for IOMMU
>
> On 15/11/19 1:07 PM, haibo.chen@xxxxxxx wrote:
> > From: Haibo Chen <haibo.chen@xxxxxxx>
> >
> > The default max segment size of IOMMU is 64KB, which exceed the ADMA
> > limitation if ADMA only support max to 65535, 64KB - 1Byte. IOMMU will
> > optimize the segments it received, merge the little segment into one
> > big segment. If we use the default IOMMU config, then ADMA will get
> > some segments which it's size is 64KB. Then ADMA error will shows up.
> >
> > Signed-off-by: Haibo Chen <haibo.chen@xxxxxxx>
> > ---
> > drivers/mmc/host/sdhci.c | 16 ++++++++++++++--
> > 1 file changed, 14 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index
> > 1436cc9c5f82..3a8093de26c7 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -3743,6 +3743,7 @@ static inline bool sdhci_can_64bit_dma(struct
> > sdhci_host *host) int sdhci_setup_host(struct sdhci_host *host) {
> > struct mmc_host *mmc;
> > + struct device *dev;
> > u32 max_current_caps;
> > unsigned int ocr_avail;
> > unsigned int override_timeout_clk;
> > @@ -3754,6 +3755,7 @@ int sdhci_setup_host(struct sdhci_host *host)
> > return -EINVAL;
> >
> > mmc = host->mmc;
> > + dev = mmc_dev(mmc);
> >
> > /*
> > * If there are external regulators, get them. Note this must be
> > done @@ -4224,10 +4226,20 @@ int sdhci_setup_host(struct sdhci_host
> *host)
> > * be larger than 64 KiB though.
> > */
> > if (host->flags & SDHCI_USE_ADMA) {
> > - if (host->quirks & SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC)
> > + if (host->quirks & SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC) {
> > mmc->max_seg_size = 65535;
> > - else
> > +
> > + /*
> > + * send the ADMA limitation to IOMMU. In default,
> > + * the max segment size of IOMMU is 64KB, this exceed
> > + * the ADMA max segment limitation, which is 65535.
> > + */
> > + dev->dma_parms = devm_kzalloc(dev,
> > + sizeof(*dev->dma_parms), GFP_KERNEL);
> > + dma_set_max_seg_size(dev, SZ_64K - 1);
>
> Doesn't mmc_setup_queue() already do this?
mmc_setup_queue do call the function dma_set_max_seg_size(), but it do not give value to dev->dma_parms.
So in dma_set_max_seg_size(), it do nothing, just return -EIO.
Should I fix this in mmc_setup_queue()?
725 static inline int dma_set_max_seg_size(struct device *dev, unsigned int size)
726 {
727 if (dev->dma_parms) {
728 dev->dma_parms->max_segment_size = size;
729 return 0;
730 }
731 return -EIO;
732 }
>
> > + } else {
> > mmc->max_seg_size = 65536;
> > + }
> > } else {
> > mmc->max_seg_size = mmc->max_req_size;
> > }
> >
