Hi Jerry, 2012/11/2 Huang Changming-R66093 <r66...@freescale.com>: > Hi, Johan, > When quicks SDHCI_QUIRK_BROKEN_CARD_DETECTION is set, the driver will poll > the card status with the command CMD13 periodically, then many interrupts > will be generated, which affect the performance.
Ok, just to see if I understand the scenario correctly: SDHCI_QUIRK_BROKEN_CARD_DETECTION causes the MMC_CAP_NEEDS_POLL cap to be set, which will cause mmc_rescan to be run at a one second interval. mmc_rescan calls bus_ops->detect (mmc_sd_detect) and this in turn calls _mmc_detect_card_removed, which will do the bus_ops->alive and send CMD13. So in this case, one CMD13 is sent per second, right? Is this the cause of the performance issue? A thought: if the host hardware does have a GPIO card detect pin hooked up, would it not be possible to make this pin generate an IRQ whenever a card is inserted or removed? This is what we do in the MMCI driver, for instance (mmci_cd_irq). > Yes, some cases to detect GPIO can't be trusted, so I only just implement > this callback in eSDHC-of driver. that is to say, just when the platform > support it, this callback can be implement, if not, continue to send the > command CMD13. I'm just wondering how this will affect our system, where we use the cd GPIO to generate detect jobs on card insert/remove, but where the cd pin is not 100% synchronized with the electrical connection of the power and cmd line of the SD-card. So if I remember correctly, the cd pin may report that the card has been removed, but there is still an electric connection and the card is alive... Kind regards, Johan -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
