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mmc: davinci: Eliminate spurious interrupts

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The davinci mmc interrupt handler fills the fifo, as long as the DXRDY
or DRRDY bits are set in the status register.

If interrupts fire during this loop, they will be handled by the
handler, but the interrupt controller will still buffer these. As a
result, the handler will be called again to serve these needlessly. In
order to avoid these spurious interrupts, keep interrupts masked while
filling the fifo.

Signed-off-by: Ido Yariv <ido@wizery.com>
Tested-by: Rajashekhara, Sudhakar <sudhakar.raj@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Ido Yariv 2012-03-11 23:39:58 +02:00 committed by Chris Ball
parent 1f84b71b3f
commit be7b5622e6
1 changed files with 27 additions and 6 deletions
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33
drivers/mmc/host/davinci_mmc.c
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@ -1009,12 +1009,33 @@ static irqreturn_t mmc_davinci_irq(int irq, void *dev_id)
* by read. So, it is not unbouned loop even in the case of * by read. So, it is not unbouned loop even in the case of
* non-dma. * non-dma.
*/ */
while (host->bytes_left && (status & (MMCST0_DXRDY | MMCST0_DRRDY))) { if (host->bytes_left && (status & (MMCST0_DXRDY | MMCST0_DRRDY))) {
davinci_fifo_data_trans(host, rw_threshold); unsigned long im_val;
status = readl(host->base + DAVINCI_MMCST0);
if (!status) /*
break; * If interrupts fire during the following loop, they will be
qstatus |= status; * handled by the handler, but the PIC will still buffer these.
* As a result, the handler will be called again to serve these
* needlessly. In order to avoid these spurious interrupts,
* keep interrupts masked during the loop.
*/
im_val = readl(host->base + DAVINCI_MMCIM);
writel(0, host->base + DAVINCI_MMCIM);
do {
davinci_fifo_data_trans(host, rw_threshold);
status = readl(host->base + DAVINCI_MMCST0);
qstatus |= status;
} while (host->bytes_left &&
(status & (MMCST0_DXRDY | MMCST0_DRRDY)));
/*
* If an interrupt is pending, it is assumed it will fire when
* it is unmasked. This assumption is also taken when the MMCIM
* is first set. Otherwise, writing to MMCIM after reading the
* status is race-prone.
*/
writel(im_val, host->base + DAVINCI_MMCIM);
} }
if (qstatus & MMCST0_DATDNE) { if (qstatus & MMCST0_DATDNE) {