linux-kernel - Avoid needless loop in sdhci

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Date:	Wed, 09 Oct 2013 22:26:49 -0700
From:	Alexey Neyman <stilor@....net>
To:	Chris Ball <cjb@...top.org>, linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Avoid needless loop in sdhci_irq() for Card Interrupt

Hi all,

I've discovered that the sdhci_irq() function needlessly iterates re-reading 
the interrupt status and doing nothing (until it runs out of max_loops) when 
it handles the "Card Interrupt" status in the interrupt status register.

The reason is that the "Card Interrupt" bit is not cleared until the 
sdhci_irq() calls mmc_signal_sdio_irq(), so if Card Interrupt was asserted, 
re-reading the interrupt status will find this bit set over and over, even if 
no other bits are reported.

The fix: ignore Card Interrupt bits in the interrupt status if we already know 
that mmc_signal_sdio_irq() is going to be called at the end of sdhci_irq().

Signed-off-by: Alexey Neyman <stilor@....net>

View attachment "sdhci.c.diff" of type "text/x-patch" (689 bytes)