From: Eric Nelson [eric.nelson@boundarydevices.com] Sent: Tuesday, April 02, 2013 19:49 To: Gabbasov, Andrew Cc: u-boot@lists.denx.de Subject: Re: [U-Boot] [PATCH] mx6: fsl_esdhc: Fix waiting for DMA operation completion
Thanks Andrew,
On 04/02/2013 03:04 AM, Andrew Gabbasov wrote:
On iMX6 sometimes the Transfer Complete interrupt occurs earlier than the DMA part completes its operation. If immediately after that the read data is used for some data verification, those obtained data may be incomplete, which causes intermittent verification failures.
Can you describe how to repeat this?
For example, when the default environment command tries to load and run boot script from FAT partition on SD/MMC card, it sometimes fails, reporting invalid partition table, or unknown partition type, or something else of that kind. Such errors disappear if the build configuration has CONFIG_SYS_FSL_ESDHC_USE_PIO, or if some delay is added after transfer completion.
We do this on every boot on SABRE Lite and Nitrogen6x boards, and haven't seen an issue.
What board are you testing on?
Do you have cache enabled?
Is this with an SD card or eMMC?
Hi Eric,
Thank you for the response.
I'm using SabreLite with SD card.
For reproducing a problem I took the latest version of U-Boot from master branch and made a couple of changes in include/configs/mx6qsabrelite.h: - removed duplication of "mmc dev ${mmcdev};" in CONFIG_BOOTCOMMAND; - and changed CONFIG_ENV_IS_IN_MMC to CONFIG_ENV_IS_NOWHERE (thus disabling to try reading saved environment from mmc). The boot.scr contains a single command "printenv". When I'm doing resets with this configuration, I'm getting errors in MMC access approximately once per 4-5 boots. The errors can be "Invalid partition 2" or "No partition table".
Indeed, I was unable to reproduce it with plain master version, but 2 simple changes in configuration, described above, allowed me to reproduce it.
Thanks.
Best regards, Andrew
Adding extra waiting for DMA completion after Transfer Complete event fixes this issue.
Signed-off-by: Andrew Gabbasov andrew_gabbasov@mentor.com
drivers/mmc/fsl_esdhc.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c index d2a505e..806c6dd 100644 --- a/drivers/mmc/fsl_esdhc.c +++ b/drivers/mmc/fsl_esdhc.c @@ -402,6 +402,12 @@ esdhc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data) return COMM_ERR; } while (!(irqstat & IRQSTAT_TC) && (esdhc_read32(®s->prsstat) & PRSSTAT_DLA)); +#ifdef CONFIG_MX6
/* In imx6 TC (data end) interrupt sometimes occur earlierthan DMA completes. In this case just wait a little more. */while (!(irqstat & (IRQSTAT_DINT | IRQSTAT_DMAE)))irqstat = esdhc_read32(®s->irqstat);+#endif #endif }