Hello Sir,
This timming issue looks strange, it has something to do with the u-boot base version upgrading, any comments?
Best regards, Aaron
---------- Forwarded message ---------- From: Aaron Wu aaronwu06@gmail.com Date: Tue, Aug 16, 2011 at 12:36 PM Subject: SD/MMC timming issue when upgrading from 2010.09 to 2010.12 version To: u-boot@lists.denx.de
Hello Sir,
I am using the u-boot on a blackfin board. When upgrading the u-boot from version 2010.09 to 2010.12 I met a a problem which looks like timming related. I'm doing the following test with a Sandisk 256MB SD card.
mmc rescan 0 fatls mmc 0
with 2010.09 version everything works fine, with 2010.12 version I will have to add a delay as the following patch indicates to pass the test. Or it will fail when calling the mmc_startup function in the mmc_send_cmd function when trying to do the sd_change_freq according to my debug. It returns a -18 error which means a communication error, to be specific, it's a hardware data crc error happened on my specific SD controller. While actually the driver code for my controller is identical for both versions.
Since adding a delay would pass the test I guess it would be a timming issue, could some one please shed some light?
Thanks Aaron
--- drivers/mmc/mmc.c 2011-08-16 12:31:53.293745081 +0800 +++ drivers/mmc/mmc_new.c 2011-08-16 12:34:02.597745252 +0800 @@ -635,6 +635,7 @@ cmd.flags = 0;
err = mmc_send_cmd(mmc, &cmd, NULL); + delay(2000);
if (err) return err;