[U-Boot] [PATCH] spi: tegra: fix hand in set_mode()

[Jagan Teki]

On 18 August 2016 at 22:23, Stephen Warren <swarren at wwwdotorg.org> wrote:
> From: Stephen Warren <swarren at nvidia.com>
>
> In tegra20_slink.c, the set_mode() function may be executed before the
> SPI bus is claimed the first time, and hence the clocks to the SPI
> controller may not be running. If so, any register read/write at this
> time will hang the CPU. Fix this by ensuring the clock is running as soon
> as the driver is probed. This is observed on the Tegra30 Beaver board.
>
> Apply the same clock initialization fix to all other Tegra SPI drivers so
> that if set_mode() is ever implemented there, the same bug will not appear.
> Note that tegra114_spi.c already operates in this fashion.
>
> The clock manipulation code is copied from claim_bus() to probe() rather
> than moved. This ensures that any calls to set_speed() take effect; the
> clock can't be set once during probe and left unchanged.

Do we need to set the clock for claim_bus() as well? I think it's
better to move this on to set_speed so-that any call to set_speed()
will update the same. I don't think claim_bus would require this
again.

thanks!
-- 
Jagan Teki
Free Software Engineer | www.openedev.com
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.