Tejun Heo wrote:
With ATAPI transfer chunk size properly programmed, libata PIO HSM
should be able to handle full spurious data chunks. Also, it's a good
idea to suppress trailing data warning for misc ATAPI commands as
there can be many of them per command - for example, if the chunk size
is 16 and the drive tries to transfer 510 bytes, there can be 31
trailing data messages.
This patch makes the following updates to libata ATAPI PIO HSM
implementation.
* Make it drain full spurious chunks.
* Suppress trailing data warning message for misc commands.
* Put limit on how many bytes can be drained.
* If odd, round up consumed bytes and the number of bytes to be
drained. This gets the number of bytes to drain right for drivers
which do 16bit PIO.
This patch is partial backport of improve-ATAPI-data-xfer patchset
pending for #upstream.
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
---
This combined with the previous patch fixes bug 9346.
drivers/ata/libata-core.c | 87 ++++++++++++++++++++++++++++++++++------------
include/linux/libata.h | 2 +
2 files changed, 67 insertions(+), 22 deletions(-)
Index: work/drivers/ata/libata-core.c
===================================================================
--- work.orig/drivers/ata/libata-core.c
+++ work/drivers/ata/libata-core.c
@@ -64,6 +64,7 @@
#include <linux/libata.h>
#include <asm/semaphore.h>
#include <asm/byteorder.h>
+#include <linux/cdrom.h>
#include "libata.h"
@@ -4649,6 +4650,43 @@ int ata_check_atapi_dma(struct ata_queue
}
/**
+ * atapi_qc_may_overflow - Check whether data transfer may overflow
+ * @qc: ATA command in question
+ *
+ * ATAPI commands which transfer variable length data to host
+ * might overflow due to application error or hardare bug. This
+ * function checks whether overflow should be drained and ignored
+ * for @qc.
+ *
+ * LOCKING:
+ * None.
+ *
+ * RETURNS:
+ * 1 if @qc may overflow; otherwise, 0.
+ */
+static int atapi_qc_may_overflow(struct ata_queued_cmd *qc)
+{
+ if (qc->tf.protocol != ATA_PROT_ATAPI &&
+ qc->tf.protocol != ATA_PROT_ATAPI_DMA)
+ return 0;
+
+ if (qc->tf.flags & ATA_TFLAG_WRITE)
+ return 0;
+
+ switch (qc->cdb[0]) {
+ case READ_10:
+ case READ_12:
+ case WRITE_10:
+ case WRITE_12:
+ case GPCMD_READ_CD:
+ case GPCMD_READ_CD_MSF:
+ return 0;
+ }
+
+ return 1;
applied, though I hope we can eventually find a better solution...
-
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