[PATCH 0/4] Extend sdhci-esdhc-imx card_detect and write_protect support for mx5

Arnaud Patard (Rtp) arnaud.patard at rtp-net.org
Thu Jun 16 14:32:33 EDT 2011

Shawn Guo <shawn.guo at freescale.com> writes:


> On Fri, Jun 10, 2011 at 06:42:48PM +0800, Shawn Guo wrote:
>> The card-present polling within sdhci based driver is very expensive
>> in terms of the impact to system performance.  We observe a few
>> system performance issues from Freescale and Linaro on mx5 platforms,
>> which have been proved card polling related.
>> The patch set extends the current sdhci-esdhc-imx card_detect and
>> write_protect support to cover mx5 platforms, and solves above
>> performance issues.
>> Shawn Guo (4):
>>       mmc: sdhci: fix interrupt storm from card detection
>>       mmc: sdhci-esdhc-imx: SDHCI_CARD_PRESENT does not get cleared
>>       mmc: sdhci-esdhc-imx: remove "WP" from flag ESDHC_FLAG_GPIO_FOR_CD_WP
>>       mmc: sdhci-esdhc-imx: extend card_detect and write_protect support
> Hi Arnaud,
> Any chance to play with it yet?

Finally managed to build a kernel with this version of the
patchset. While I'm not polling anymore, I'm getting a lot of interrupts
if the card is not inserted. Theses interrupts are not happening if the
card is inserted. I can see things like this in the logs :
sdhci [sdhci_irq()]: *** mmc0 got interrupt: 0x00000080

[ of course, the bit of the present state register indicating card
presence is equal to 0 ]

I've tested the SIGNAL case only. Don't know if switch to GPIO may help.
Do you have same kind of issue on your side ?


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