Re: [PATCH 3/4] drivers: ata: wake port before DMA stop for ALPM
From: Tejun Heo <tj@kernel.org>
Date: 2016-01-08 16:36:14
Also in:
linux-arm-kernel, lkml
Hello, On Thu, Jan 07, 2016 at 04:03:32PM -0800, Florian Fainelli wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index d61740e78d6d..b6664c579f9a 100644 --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c@@ -595,6 +595,58 @@ int ahci_stop_engine(struct ata_port *ap) void __iomem *port_mmio = ahci_port_base(ap); u32 tmp; + /* + * On some controllers, stopping a port's DMA engine + * while the port is in ALPM state (partial or slumber) + * results in failures on subsequent DMA engine starts. + * For those controllers, put the port back in active + * state before stopping it's DMA engine. + */ + if (ap->flags2 & ATA_FLAG2_WAKE_BEFORE_STOP) {
... So, I'm not too comfortable with open coding ALPM switching in ahci_stop_engine(). Shouldn't it be possible to update and/or refactor and reuse ahci_set_lpm()?
quoted hunk ↗ jump to hunk
--- a/include/linux/libata.h +++ b/include/linux/libata.h@@ -236,6 +236,8 @@ enum { /* bits 24:31 of ap->flags are reserved for LLD specific flags */ + /* struct ata_port flags2 */ + ATA_FLAG2_WAKE_BEFORE_STOP = (1 << 0), /* wake link before DMA stop */
What's wrong with bits 2-5 in ATA_FLAG_* space? Also, should this be a ahci priv flag? Thanks. -- tejun