From fb3296335500aaff61333df8eabbccf28761c79d Mon Sep 17 00:00:00 2001 From: Danesh Petigara Date: Mon, 11 Jan 2016 13:22:26 -0800 Subject: drivers: ata: wake port before DMA stop for ALPM The AHCI driver code stops and starts port DMA engines at will without considering the power state of the particular port. The AHCI specification isn't very clear on how to handle this scenario, leaving implementation open to interpretation. Broadcom's STB SATA host controller is unable to handle port DMA controller restarts when the port in question is in low power mode. When a port enters partial or slumber mode, its PHY is powered down. When a controller restart is requested, the controller's internal state machine expects the PHY to be brought back up by software which never happens in this case, resulting in failures. To avoid this situation, logic is added to manually wake up the port just before its DMA engine is stopped, if the port happens to be in a low power state. HBA initiated power management ensures that the port eventually returns to its configured low power state, when the link is idle (as per the conditions listed in the spec). A new host flag is also added to ensure this logic is only exercised for hosts with the above limitation. tj: Formatting changes. Signed-off-by: Danesh Petigara Reviewed-by: Markus Mayer Signed-off-by: Tejun Heo --- drivers/ata/ahci.h | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/ata/ahci.h') diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h index a4faa438889c..a44c75d4c284 100644 --- a/drivers/ata/ahci.h +++ b/drivers/ata/ahci.h @@ -250,6 +250,7 @@ enum { AHCI_HFLAG_MULTI_MSI = 0, AHCI_HFLAG_MULTI_MSIX = 0, #endif + AHCI_HFLAG_WAKE_BEFORE_STOP = (1 << 22), /* wake before DMA stop */ /* ap->flags bits */ -- cgit v1.2.1