On Thursday, November 05, 2015 at 03:53:16 PM, Gregory CLEMENT wrote:
Timing issue occurs on eMMC not only when modifying the frequency but also for all the switch command(CMD6). According to the MMC spec waiting 8 clocks after a switch command would be the thing to do.
This patch allows fixing CPU hang observed when trying to changing the bus width on a eMMC on SAMA5D4.
Signed-off-by: Gregory CLEMENT gregory.clement@free-electrons.com
On DENX MA5D4EVK:
Tested-by: Marek Vasut marex@denx.de
[...]
@@ -284,8 +286,10 @@ mci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data) { u32 cnt = word_count * 4; printf("Read Data:\n");
/* print_buffer(0, data->dest + cnt * block_count, 1, cnt, 0);*/
This bit shouldn't be in the patch I guess ;-)
}#endif #ifdef DEBUG @@ -323,6 +327,12 @@ mci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data) } }
- /* After the switch command, wait for 8 clocks before the next
* command*/
The comment style should match the kernel one -- multilines go like this: /* * foo * bar */
- if (cmd->cmdidx == MMC_CMD_SWITCH)
udelay(8*1000000/ priv->curr_clk); /* 8 clk in us*/- return 0;
}
Best regards, Marek Vasut