On Wed, 12 May 2010 10:50:45 +0300
Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> >From ad2e1cd024ccf9144b6620cfe808893719db738f Mon Sep 17 00:00:00 2001
> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Date: Wed, 14 Apr 2010 16:26:45 +0300
> Subject: [PATCH] omap_hsmmc: improve interrupt synchronisation
>
> The following changes were needed:
> - do not use in_interrupt() because it will not work
> with threaded interrupts
>
> In addition, the following improvements were made:
> - ensure DMA is unmapped only after the final DMA interrupt
> - ensure a request is completed only after the final DMA interrupt
> - disable controller interrupts when a request is not in progress
> - remove the spin-lock protecting the start of a new request from
> an unexpected interrupt because the locking was complicated and
> a 'req_in_progress' flag suffices (since the spin-lock only defers
> the unexpected interrupts anyway)
> - instead use the spin-lock to protect the MMC interrupt handler
> from the DMA interrupt handler
> - remove the semaphore preventing DMA from being started while
> the previous DMA is still in progress - the other changes make that
> impossible, so it is now a BUG_ON condition
> - ensure the controller interrupt status is clear before exiting
> the interrrupt handler
>
> In general, these changes make the code safer but do not fix any specific
> bugs so backporting is not necessary.
>
>
> ...
>
> +static void omap_hsmmc_request_done(struct omap_hsmmc_host *host, struct mmc_request *mrq)
> +{
> + int dma_ch;
> +
> + spin_lock(&host->irq_lock);
> + host->req_in_progress = 0;
> + dma_ch = host->dma_ch;
> + spin_unlock(&host->irq_lock);
> +
> + omap_hsmmc_disable_irq(host);
> + /* Do not complete the request if DMA is still in progress */
> + if (mrq->data && host->use_dma && dma_ch != -1)
> + return;
> + host->mrq = NULL;
> + mmc_request_done(host->mmc, mrq);
> +}
Are we sure that irq_lock doesn't need to be taken in an irq-safe fashion?
send_init_stream() doesn't report an error if its busywait times out.
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