From: Rasmus Villemoes linux@rasmusvillemoes.dk
commit 8b6dc6b2d60221e90703babbc141f063b8a07e72 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/mmc/host/sdhci-of-esdhc.c | 3 --- 1 file changed, 3 deletions(-)
--- a/drivers/mmc/host/sdhci-of-esdhc.c +++ b/drivers/mmc/host/sdhci-of-esdhc.c @@ -615,9 +615,6 @@ static void esdhc_reset(struct sdhci_hos 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;