On 03/17/2014 09:51 AM, Franky Lin wrote:
Hi Ulf,
On 03/17/2014 02:12 AM, Ulf Hansson wrote:
On 7 January 2014 19:37, Franky Lin <frankyl@xxxxxxxxxxxx> wrote:
For high clock frequency modes, ie. SDR104 and possibly SDR50, the data
window on the CMD and DAT lines needs to be tuned. Once tuned to a
sample clock rate, a re-tuning might required because of drifted signal
on different lines. This re-tuning is needed and only necessary for
commands using the DAT lines, ie. adtc type commands. This patch is an
optimization by adding the condition of the requested command being
adtc
type in order to execute the re-tuning procedure.
Signed-off-by: Franky Lin <frankyl@xxxxxxxxxxxx>
Hi Franky,
Sorry for the delay.
---
drivers/mmc/host/sdhci.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index cc00bed..f301cd6 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1389,7 +1389,8 @@ static void sdhci_request(struct mmc_host
*mmc, struct mmc_request *mrq)
* tuning procedure before sending command.
*/
if ((host->flags & SDHCI_NEEDS_RETUNING) &&
- !(present_state & (SDHCI_DOING_WRITE |
SDHCI_DOING_READ))) {
+ !(present_state & (SDHCI_DOING_WRITE |
SDHCI_DOING_READ)) &&
+ mmc_cmd_type(mrq->cmd) == MMC_CMD_ADTC) {
I don't have the in-depth knowledge about the sdhci; Still, to me it
seems like checking for MMC_CMD_ADTC, is that not just the same a
checking if there are a READ/WRITE?
non-adtc commands like CMD17/CMD24/CMD52 do not use the data lines.
Tuning is only necessary for adtc commands as CMD18/CMD25/CMD53 which
involve data lines.
Another note, we really should be working on moving the periodic
"re-tuning trigger" mechanism into the mmc core layer, so all host
driver's could benefit from this. Do you want to help out fixing this?
I thought about this before but hesitated because of non-sdhci
drivers. I have seen some of them don't have standardized
implementation(well if they do they would have used sdhci anyway).
Ping?
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