Re: [PATCH v4] mmc: fix async request mechanism for sequential read scenarios

[Konstantin Dorfman <kdorfman@codeaurora.org>]

On 12/06/2012 07:24 AM, Seungwon Jeon wrote:
> Hi,
> 
> Doesn't it consider SD path?
> It have a problem with uninitialized 'context_info'.
> 'context_info' is moved into mmc_host struct in v4.
> Please, could you explain the reason in brief?
> 

The problem I'm trying to resolve with the v4 change is: there should be
no core/core.c API change from upper layers point of view.

There was such violation, when the synchronization mechanism of async
request for data commands was changed (from "completion" to "wait_event"
+ number of flags to pass event reason).

Before v4, the 'context_info' initialized by mmc_init_queue() function
and this is valid only for mmcblk. For example when running the mmc_test
module, the code for card/queue.c, card/block.c layers is not run at all
and the struct remains uninitialized.

In the current version the initialization was moved into
mmc_attach_mmc(), but now, I understand, that this initialization should
be moved even before mmc_attach_XXX() (XXX is sdio/sd/mmc...) - it may
be placed in  mmc_rescan_try_freq().

Will resend v4 after the testing.

'mmc_host' structure contains a host information for all sdio/sd/mmc, so
'context_info' may be accessed by any protocol willing to use
NEW_REQUEST notification (when async request mechanism is used).

-- 
Konstantin Dorfman,
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center,
Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation