Re: [PATCH 1/3] mmc: sdhci-cadence: enable v4_mode to fix ADMA 64-bit addressing

[Masahiro Yamada]

On Thu, Aug 29, 2019 at 8:48 PM Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>
> On Thu, 29 Aug 2019 at 12:49, Masahiro Yamada
> <yamada.masahiro@xxxxxxxxxxxxx> wrote:
> >
> > The IP datasheet says this controller is compatible with SD Host
> > Specification Version v4.00.
> >
> > As it turned out, the ADMA of this IP does not work with 64-bit mode
> > when it is in the Version 3.00 compatible mode; it understands the
> > old 64-bit descriptor table (as defined in SDHCI v2), but the ADMA
> > System Address Register (SDHCI_ADMA_ADDRESS) cannot point to the
> > 64-bit address.
> >
> > I noticed this issue only after commit bd2e75633c80 ("dma-contiguous:
> > use fallback alloc_pages for single pages"). Prior to that commit,
> > dma_set_mask_and_coherent() returned the dma address that fits in
> > 32-bit range, at least for the default arm64 configuration
> > (arch/arm64/configs/defconfig). Now the host->adma_addr exceeds the
> > 32-bit limit, causing the real problem for the Socionext SoCs.
> > (As a side-note, I was also able to reproduce the issue for older
> > kernels by turning off CONFIG_DMA_CMA.)
> >
> > Call sdhci_enable_v4_mode() to fix this.
> >
> > I think it is better to back-port this, but only possible for v4.20+.
> >
> > When this driver was merged (v4.10), the v4 mode support did not exist.
> > It was added by commit b3f80b434f72 ("mmc: sdhci: Add sd host v4 mode")
> > i.e. v4.20.
> >
> > Cc: <stable@xxxxxxxxxxxxxxx> # v4.20+
> > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
>
> Applied for fixes, by adding below tag, thanks!
>
> Fixes: b3f80b434f72 ("mmc: sdhci: Add sd host v4 mode")

This is not a bug commit.





-- 
Best Regards
Masahiro Yamada