From 8b6dc6b2d60221e90703babbc141f063b8a07e72 Mon Sep 17 00:00:00 2001

From: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Date: Wed, 4 Dec 2019 09:54:46 +0100

Subject: [PATCH] mmc: sdhci-of-esdhc: Revert "mmc: sdhci-of-esdhc: add erratum A-009204 support"

Git-commit: 8b6dc6b2d60221e90703babbc141f063b8a07e72

Patch-mainline: v5.5-rc3

References: bsc#1051510

This reverts commit 5dd195522562542bc6ebe6e7bd47890d8b7ca93c.

First, the fix seems to be plain wrong, since the erratum suggests

waiting 5ms before setting setting SYSCTL[RSTD], but this msleep()

happens after the call of sdhci_reset() which is where that bit gets

set (if SDHCI_RESET_DATA is in mask).

Second, walking the whole device tree to figure out if some node has a

"fsl,p2020-esdhc" compatible string is hugely expensive - about 70 to

100 us on our mpc8309 board. Walking the device tree is done under a

raw_spin_lock, so this is obviously really bad on an -rt system, and a

waste of time on all.

In fact, since esdhc_reset() seems to get called around 100 times per

second, that mpc8309 now spends 0.8% of its time determining that

it is not a p2020. Whether those 100 calls/s are normal or due to some

other bug or misconfiguration, regularly hitting a 100 us

non-preemptible window is unacceptable.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Cc: stable@vger.kernel.org

Link: https://lore.kernel.org/r/20191204085447.27491-1-linux@rasmusvillemoes.dk

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/mmc/host/sdhci-of-esdhc.c | 3 ---

 1 file changed, 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c

index 5cca3fa4610b..7f87a90bf56a 100644

--- a/drivers/mmc/host/sdhci-of-esdhc.c

+++ b/drivers/mmc/host/sdhci-of-esdhc.c

@@ -764,9 +764,6 @@ static void esdhc_reset(struct sdhci_host *host, u8 mask)

 	sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);

 	sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);

-	if (of_find_compatible_node(NULL, NULL, "fsl,p2020-esdhc"))

-		mdelay(5);

-

 	if (mask & SDHCI_RESET_ALL) {

 		val = sdhci_readl(host, ESDHC_TBCTL);

 		val &= ~ESDHC_TB_EN;

-- 

2.16.4