On Wed, Apr 6, 2011 at 2:58 AM, Stephen Warren <swarren@xxxxxxxxxx> wrote: > Kishore Kadiyala wrote at Tuesday, April 05, 2011 12:38 AM: >> >> Hi Stephen, >> >> On Mon, Apr 4, 2011 at 11:09 PM, Stephen Warren <swarren@xxxxxxxxxx> wrote: >> > Chris et. al., >> > >> > I'm working on an ARM system that contains at least two MMC/SD devices; >> > specifically the board has an internal MMC device, and an SD card slot, >> > although the SoC has four MMC/SD hosts IIRC. >> > >> > The kernel's naming of these devices is dynamic. If the SD card is not >> > plugged in, the internal MMC is always known as mmcblock0. If the SD card >> > is plugged in too, sometimes the internal MMC is mmcblk0 and sometimes it's >> > mmcblk1. I assume this is timing related; 2.6.37 usually seemed to name >> > them "in order", whereas 2.6.38 usually seems to name them "backwards". >> > >> > This causes problems with the bootloader scripts I'm using, which assumes >> > that the internal MMC is always device 0 and the SD slot is always device 1, >> > and hence provides kernel command-line argument root=/dev/mmcblk0p3 or >> > root=/dev/mmcblk1p3 based on whether it booted from SD or internal MMC (SD >> > is searched for a valid image first by the bootloader). >> >> Just follow this thread which discusses the same but for OMAP4 controller >> http://www.mail-archive.com/linux-omap@xxxxxxxxxxxxxxx/msg47853.html > > Kishore, thanks for the pointer. However, I don't see anything in that thread > that affects MMC block device IDs. The thread ended with the original poster > requesting the patch be dropped, since he'd made a mistake in his bootloader > settings. > > Just perhaps the registration order change is enough to change the timing of > device (memory device, not host controller?) probing, which just happens to > affect the ID assignment? > >> One solution could be make your internal MMC always registered as mmcblk0 >> and the removable one as next device. > > That's essentially what the patch I gave previously does. Your change was in mmc/card/block.c, but you can handle this by changing sequence during device registeration. Following change in the patch does that https://patchwork.kernel.org/patch/595861/ diff --git a/arch/arm/mach-omap2/board-4430sdp.c b/arch/arm/mach-omap2/board-4430sdp.c index 1a943be..f914099 100644 --- a/arch/arm/mach-omap2/board-4430sdp.c +++ b/arch/arm/mach-omap2/board-4430sdp.c @@ -349,11 +349,6 @@ static struct twl4030_usb_data omap4_usbphy_data = { static struct omap2_hsmmc_info mmc[] = { { - .mmc = 1, - .caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA, - .gpio_wp = -EINVAL, - }, - { .mmc = 2, .caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA, .gpio_cd = -EINVAL, @@ -361,19 +356,24 @@ static struct omap2_hsmmc_info mmc[] = { .nonremovable = true, .ocr_mask = MMC_VDD_29_30, }, + { + .mmc = 1, + .caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA, + .gpio_wp = -EINVAL, + }, {} /* Terminator */ }; Regards, Kishore > > -- > nvpublic > > -- 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
