Hi, Andy Could you give some reason why eMMC device will be so slowed down by re-initialization? I think eMMC device is initialized only once, except it invoke 'mmc_init' many times.
The workaround "mmc rescan" works when replace the card. But if one card is removed, then use "mmcfinfo": there is no card present, while the previous card information is displayed, I don't' think it make sense. => mmc rescan MMC: no card present => mmcinfo MMC: no card present Device: FSL_SDHC Manufacturer ID: 2 OEM: 544d Name: SD04G Tran Speed: 50000000 Rd Block Len: 512 SD version 2.0 High Capacity: Yes Capacity: 3.7 GiB Bus Width: 4-bit
Best Regards Jerry Huang
-----Original Message----- From: Andy Fleming [mailto:afleming@gmail.com] Sent: Saturday, July 14, 2012 5:33 AM To: Huang Changming-R66093 Cc: u-boot@lists.denx.de; Marek Vasut Subject: Re: [PATCH 1/2 v2] SDHC/MMC: fix the wrong infomation after change SD card
On Wed, Jul 11, 2012 at 4:29 AM, Huang Changming-R66093 r66093@freescale.com wrote:
Hi, Andy, There is not any feedback for very long time, Could it be applied to the u-boot?
I'm afraid I have to reject this patch. We need to find a better solution to the two problems:
- We want to change cards and still have mmc commands work
- We don't want eMMC devices to be slowed down by constantly
re-initializing their cards.
Normally, I would err on the side of #1, but there's a simple workaround. If you replace the card, execute "mmc rescan", and the card will be reinitialized. Please let me know if that workaround doesn't work. I hope, in the future, we'll have some code which makes both possible, by being able to detect that a card has been changed, but for now I think the current system is reasonably satisfactory to both cases #1 and #2.
Andy