Andrew Morton wrote:
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?
It is OK at the moment. It is only used in interrupt handlers which currently do run in interrupt context with IRQF_DISABLED. If both DMA and MMC interrupt handlers were changed to be threaded interrupts, then the spin-lock would still be OK. But if only one of them was changed, then the spin-lock would have to be changed to be irq-safe.
send_init_stream() doesn't report an error if its busywait times out.
It is not a problem. It may mean the card does not initialize but if that happens there will be lots more errors. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
