[U-Boot] [PATCH 4/5] mmc: tegra: allow disabling external clock loopback

[Simon Glass]

On 1 December 2016 at 00:40, Marcel Ziswiler <marcel at ziswiler.com> wrote:
>
>
> On December 1, 2016 3:20:55 AM GMT+01:00, Simon Glass <sjg at chromium.org> wrote:
>>Hi Marcel,
>>
>>On 30 November 2016 at 09:47, Marcel Ziswiler <marcel at ziswiler.com>
>>wrote:
>>> From: Marcel Ziswiler <marcel.ziswiler at toradex.com>
>>>
>>> Introduce CONFIG_TEGRA124_MMC_DISABLE_EXT_LOOPBACK to disable the
>>external clock
>>> loopback and use the internal one on SDMMC3 as per the
>>SDMMC_VENDOR_MISC_CNTRL_0
>>> register's SDMMC_SPARE1 bits being set to 0xfffd according to the
>>TRM.
>>>
>>> Signed-off-by: Marcel Ziswiler <marcel.ziswiler at toradex.com>
>>> ---
>>>
>>>  arch/arm/include/asm/arch-tegra/tegra_mmc.h |  2 ++
>>>  drivers/mmc/Kconfig                         |  8 ++++++++
>>>  drivers/mmc/tegra_mmc.c                     | 13 +++++++++++++
>>>  3 files changed, 23 insertions(+)
>>
>>This should be controlled by the device tree, shouldn't it?
>
> Glad you brought it up. So far NVIDIA hasn't even acknowledged that they completely seriously screwed this one up big time. Unlike their PCIe bug I reported which eventually did make it to the errata... Anyway, my hopes were kind of to sneak this one into U-Boot first, then work on a proper kernel integration probably involving device tree integration and only in a later third step maybe updating this in U-Boot again.

OK, please can you add a TODO(email) in there so it is clear this is temporary?

Reviewed-by: Simon Glass <sjg at chromium.org>