libata: Add atapi_dmadir force flag

Some device require DMADIR to be enabled, but are not detected as such
by atapi_id_dmadir.  One such example is "Asus Serillel 2"
SATA-host-to-PATA-device bridge: the bridge itself requires DMADIR,
even if the bridged device does not.

As atapi_dmadir module parameter can cause problems with some devices
(as per Tejun Heo's memory), enabling it globally may not be possible
depending on the hardware.

This patch adds atapi_dmadir in the form of a "force" horkage value,
allowing global, per-bus and per-device control.

Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

3 files changed, 5 insertions, 1 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index c3bfacb92910..489815e3e484 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1456,6 +1456,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
                         * dump_id: dump IDENTIFY data.
 
+                        * atapi_dmadir: Enable ATAPI DMADIR bridge support
+
                         If there are multiple matching configurations changing
                         the same attribute, the last one is used.
 
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 5f7d5f9ee820..c97a244c099a 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2395,7 +2395,7 @@ int ata_dev_configure(struct ata_device *dev)
                         cdb_intr_string = ", CDB intr";
                 }
 
-                if (atapi_dmadir || atapi_id_dmadir(dev->id)) {
+                if (atapi_dmadir || (dev->horkage & ATA_HORKAGE_ATAPI_DMADIR) || atapi_id_dmadir(dev->id)) {
                         dev->flags |= ATA_DFLAG_DMADIR;
                         dma_dir_string = ", DMADIR";
                 }
@@ -6496,6 +6496,7 @@ static int __init ata_parse_force_one(char **cur,
                 { "nosrst",     .lflags         = ATA_LFLAG_NO_SRST },
                 { "norst",      .lflags         = ATA_LFLAG_NO_HRST | ATA_LFLAG_NO_SRST },
                 { "rstonce",    .lflags         = ATA_LFLAG_RST_ONCE },
+                { "atapi_dmadir", .horkage_on   = ATA_HORKAGE_ATAPI_DMADIR },
         };
         char *start = *cur, *p = *cur;
         char *id, *val, *endp;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 47e029236f6e..c886dc87aa81 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -399,6 +399,7 @@ enum {
         ATA_HORKAGE_BROKEN_FPDMA_AA     = (1 << 15),    /* skip AA */
         ATA_HORKAGE_DUMP_ID     = (1 << 16),    /* dump IDENTIFY data */
         ATA_HORKAGE_MAX_SEC_LBA48 = (1 << 17),  /* Set max sects to 65535 */
+        ATA_HORKAGE_ATAPI_DMADIR = (1 << 18),   /* device requires dmadir */
 
          /* DMA mask for user DMA control: User visible values; DO NOT
             renumber */