Re: [PATCH v2] mmc: tmio: Don't access hardware registers after stopping clocks

[Simon Horman <horms@verge.net.au>]

On Tue, Jun 12, 2012 at 11:29:35PM +0200, Laurent Pinchart wrote:
> The tmio_mmc_set_ios() function configures the MMC power, clock and bus
> width. When the mmc core requests the driver to power off the card, we
> inform runtime PM, that the controller can be suspended. This can lead
> to the MSTP clock being turned off.
> 
> Writing to any 16-bit hardware registers with the MSTP clock off leads
> to timeouts and errors being printed to the kernel log. This can occur
> both when stopping the MMC clock and when configuring the bus width.
> 
> To fix this, stop the MMC clock before calling put_runtime_pm(), and
> skip bus width configuration when power is off.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Hi Laurent,

could you let me know if there is a (simple :) way for me to exercise this?

> ---
>  drivers/mmc/host/tmio_mmc_pio.c |   18 ++++++++++--------
>  1 files changed, 10 insertions(+), 8 deletions(-)