[PATCH v3 1/4] scsi: set to WCE if usb cache quirk is present.
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From: Namjae Jeon <hidden>
Date: 2012-06-09 17:41:12
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Subsystem:
scsi subsystem, the rest · Maintainers:
"James E.J. Bottomley", "Martin K. Petersen", Linus Torvalds
Make use of USB quirk method to identify such HDD while reading the cache status in sd_probe(). If cache quirk is present for the HDD, lets assume that cache is enabled and make WCE bit equal to 1. Signed-off-by: Namjae Jeon <redacted> Signed-off-by: Pankaj Kumar <redacted> Signed-off-by: Amit Sahrawat <redacted> --- drivers/scsi/sd.c | 9 +++++++-- include/scsi/scsi_device.h | 1 + 2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 6f0a4c6..e63e363 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c@@ -2259,8 +2259,13 @@ bad_sense: sd_printk(KERN_ERR, sdkp, "Asking for cache data failed\n"); defaults: - sd_printk(KERN_ERR, sdkp, "Assuming drive cache: write through\n"); - sdkp->WCE = 0; + if (sdp->wce_default_on) { + sd_printk(KERN_NOTICE, sdkp, "Assuming drive cache: write back\n"); + sdkp->WCE = 1; + } else { + sd_printk(KERN_ERR, sdkp, "Assuming drive cache: write through\n"); + sdkp->WCE = 0; + } sdkp->RCD = 0; sdkp->DPOFUA = 0; }
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 6efb2e1..8be0247 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h@@ -152,6 +152,7 @@ struct scsi_device { unsigned no_read_disc_info:1; /* Avoid READ_DISC_INFO cmds */ unsigned no_read_capacity_16:1; /* Avoid READ_CAPACITY_16 cmds */ unsigned is_visible:1; /* is the device visible in sysfs */ + unsigned wce_default_on:1; /* Cache is ON by default */ DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */ struct list_head event_list; /* asserted events */
--
1.7.9.5
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