Re: [PATCH] mmc: tegra: Disable UHS-I modes for tegra124

[Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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On Wed, Apr 13, 2016 at 03:35:56PM +0100, Jon Hunter wrote:
> Tegra124 has been randomly hanging during system suspend when entering
> the Tegra LP1 low power state. The hang is caused by the tegra SDHCI
> driver and linked to the UHS-I tuning sequence. Disabling the UHS-I
> modes for Tegra124 prevents any hangs from occurring when entering
> system suspend.
> 
> Unfortunately, the tuning sequence described in the public Tegra
> documentation is incomplete and on inspection of the current tuning
> sequence that has been implemented is also incomplete and may cause
> problems. In the short-term it is safer to disable UHS-I modes for now
> and fix later because it would be too large of a change to simply patch
> now. Therefore, disable UHS-I modes for Tegra124.
> 
> Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
> 
> I previously brought up this issue in this thread [0], but there has
> been no resolution and so I think that for v4.6 we need to disable this
> for now. I also pointered out that there is a complete implementation
> available in the v3.18 kernel used by chromeos products [1]. We do plan
> to get better support for UHS-I modes for Tegra it is just a matter of
> bandwidth at the moment :-(
> 
> [0] http://marc.info/?l=linux-tegra&m=145926947408663&w=2
> [1] https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.10/drivers/mmc/host/sdhci-tegra.c
> 
>  drivers/mmc/host/sdhci-tegra.c | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)

Other than a couple of cases of inconsistent capitalization (tegra vs.
Tegra, the latter being correct, of course), this looks fine to me:

Acked-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

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