MMC: OMAP: Do not busy wait for end of command for ever

PATCH In review Carlos Aguiar 1 participant 1 message Jan 28, 2008

Subsystems (2)

MMC, SD and SDIO OMAP MMC support

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Carlos Aguiar

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2008-01-28 19:15 UTC #0 lore raw

PATCH 18/18 MMC: OMAP: Do not busy wait for end of command for ever

From: Jarkko Lavinen <[email protected]>

The limit was a fixed 100k limit in the busy loop, which is not accurate. It would better to have time limit for the worst case which occurs when sending 80 cycles at 400 kHz and takes about 200 microseconds, so limit the max time spend in the busy loop for some 250 microseconds.

Signed-off-by Jarkko Lavinen <[email protected]>

---
 drivers/mmc/host/omap.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

drivers/mmc/host/omap.c +7 -1

index 5349f9f..c52815b 100644
@@ -1294,11 +1294,17 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 		OMAP_MMC_WRITE(host, CON, dsor);
 	slot->saved_con = dsor;
 	if (ios->power_mode == MMC_POWER_ON) {
+		/* worst case at 400kHz, 80 cycles makes 200 microsecs */
+		int usecs = 250;
+
 		/* Send clock cycles, poll completion */
 		OMAP_MMC_WRITE(host, IE, 0);
 		OMAP_MMC_WRITE(host, STAT, 0xffff);
 		OMAP_MMC_WRITE(host, CMD, 1 << 7);
-		while ((OMAP_MMC_READ(host, STAT) & 1) == 0);
+		while (usecs > 0 && (OMAP_MMC_READ(host, STAT) & 1) == 0) {
+			udelay(1);
+			usecs--;
+		}
 		OMAP_MMC_WRITE(host, STAT, 1);
 	}

-- 1.5.3.GIT