[PATCH 0/8] sdhci: Move real work out of an atomic context

Andrew Morton akpm at linux-foundation.org
Thu Jul 22 07:13:52 EST 2010

On Wed, 14 Jul 2010 17:07:28 +0400
Anton Vorontsov <avorontsov at mvista.com> wrote:

> Hi all,
> Currently the sdhci driver does everything in the atomic context.
> And what is worse, PIO transfers are made from the IRQ handler.
> This causes huge latencies (up to 120 ms). On some P2020 SOCs,
> DMA and card detection is broken, which means that kernel polls
> for the card via PIO transfers every second. Needless to say
> that this is quite bad.
> So, this patch set reworks sdhci code to avoid atomic context,
> almost completely. We only do two device memory operations
> in the atomic context, and all the rest is threaded.
> I noticed no throughput drop neither with PIO transfers nor
> with DMA (tested on MPC8569E CPU), while latencies should be
> greatly improved.

The patchset looks good to me, but it'd be nice to hear from the other
people who work on this code, please?

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