Tejun Heo wrote:
Misc ATAPI commands may try to transfer more bytes than requested.
For PIO which is performed by libata HSM, this is worked around by
draining extra bytes from __atapi_pio_bytes().
This patch implements drain buffer to perform draining for DMA and
PIO-over-DMA cases. One page is allocated w/ GFP_DMA32 during libata
core layer initialization. On host registration, this drain page is
DMA mapped and ATAPI_MAX_DRAIN_PAGES sg entries are reserved.
ata_sg_setup_extra() uses these extra sg entries to map the drain page
ATAPI_MAX_DRAIN_PAGES times, extending sg list by ATAPI_MAX_DRAIN
bytes. This allows both DMA and PIO-over-DMA misc ATAPI commands to
overflow by ATAPI_MAX_DRAIN bytes just like PIO commands.
Signed-off-by: Tejun Heo <[EMAIL PROTECTED]>
---
drivers/ata/libata-core.c | 116 ++++++++++++++++++++++++++++++++++++++++-----
drivers/ata/libata-scsi.c | 14 ++++--
include/linux/libata.h | 4 +-
3 files changed, 116 insertions(+), 18 deletions(-)
ACK this patch and #14 (implement ATAPI per-command-type DMA horkages),
but I am dropping both due to the need to be rediffed against latest
#upstream (including recent #upstream-fixes changes).
-
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
