From: Tejun Heo Date: Sat, 14 May 2011 10:28:04 +0000 (+0200) Subject: Revert "libata: ahci_start_engine compliant to AHCI spec" X-Git-Tag: firefly_0821_release~7613^2~1439 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=22fe9446e82f1fe4b59900db4599061384efb0ad;p=firefly-linux-kernel-4.4.55.git Revert "libata: ahci_start_engine compliant to AHCI spec" This reverts commit 270dac35c26433d06a89150c51e75ca0181ca7e4. The commits causes command timeouts on AC plug/unplug. It isn't yet clear why. As the commit was for a single rather obscure controller, revert the change for now. The problem was reported and bisected by Gu Rui in bug#34692. https://bugzilla.kernel.org/show_bug.cgi?id=34692 Also, reported by Rafael and Michael in the following thread. http://thread.gmane.org/gmane.linux.kernel/1138771 Signed-off-by: Tejun Heo Reported-by: Gu Rui Reported-by: Rafael J. Wysocki Reported-by: Michael Leun Cc: Jian Peng Cc: Jeff Garzik Signed-off-by: Linus Torvalds --- diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index ff9d832a163d..d38c40fe4ddb 100644 --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -561,27 +561,6 @@ void ahci_start_engine(struct ata_port *ap) { void __iomem *port_mmio = ahci_port_base(ap); u32 tmp; - u8 status; - - status = readl(port_mmio + PORT_TFDATA) & 0xFF; - - /* - * At end of section 10.1 of AHCI spec (rev 1.3), it states - * Software shall not set PxCMD.ST to 1 until it is determined - * that a functoinal device is present on the port as determined by - * PxTFD.STS.BSY=0, PxTFD.STS.DRQ=0 and PxSSTS.DET=3h - * - * Even though most AHCI host controllers work without this check, - * specific controller will fail under this condition - */ - if (status & (ATA_BUSY | ATA_DRQ)) - return; - else { - ahci_scr_read(&ap->link, SCR_STATUS, &tmp); - - if ((tmp & 0xf) != 0x3) - return; - } /* start DMA */ tmp = readl(port_mmio + PORT_CMD);