Re: [PATCH 3/5] sata_dwc: Add support ATAPI transfer
From: Sergei Shtylyov
Date: Thu May 10 2012 - 05:50:33 EST
Hello.
On 10-05-2012 8:17, Thang Q. Nguyen wrote:
Signed-off-by: Thang Q. Nguyen<tqnguyen@xxxxxxx>
---
drivers/ata/sata_dwc_460ex.c | 64 ++++++++++++++++++++++++++++++++++++++++--
1 files changed, 61 insertions(+), 3 deletions(-)
diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
index 937aeb3..6175e01 100755
--- a/drivers/ata/sata_dwc_460ex.c
+++ b/drivers/ata/sata_dwc_460ex.c
[...]
@@ -1385,6 +1389,58 @@ static void sata_dwc_port_stop(struct ata_port *ap)
ap->private_data = NULL;
}
+/**
+ * sata_dwc_check_atapi_dma - Filter ATAPI cmds which are unsuitable for DMA.
+ * @qc: queued command to check for chipset/DMA compatibility.
+ *
+ * The bmdma engines cannot handle speculative data sizes (bytecount
+ * under/over flow). So only allow DMA for data transfer commands with
+ * known data sizes.
+ */
+static int sata_dwc_check_atapi_dma(struct ata_queued_cmd *qc)
+{
[...]
+
+ /* -45150 (FFFF4FA2) to -1 (FFFFFFFF) shall use PIO mode */
Sector numbers are unsigned entities.
+ if (scmd->cmnd[0] == WRITE_10) {
+ lba = (scmd->cmnd[2] << 24) |
+ (scmd->cmnd[3] << 16) |
+ (scmd->cmnd[4] << 8) |
+ scmd->cmnd[5];
+ if (lba>= 0xFFFF4FA2)
+ pio = 1;
+ }
+ /*
+ * WORK AROUND: Fix DMA issue when blank CD/DVD disc in the drive
+ * and user use the 'fdisk -l' command. No DMA data returned so
+ * we can not complete the QC.
The user shouldn't use 'fdisk' command on CD/DVD disks. On the other
hand, he could use something like 'hdparm -t' od 'dd' with offset in which
case I'm not sure this heuristics will work.
+ */
+ else if (scmd->cmnd[0] == READ_10) {
+ lba = (scmd->cmnd[2] << 24) |
+ (scmd->cmnd[3] << 16) |
+ (scmd->cmnd[4] << 8) |
+ scmd->cmnd[5];
+ if (lba < 0x20)
+ pio = 1;
+ }
+ }
+ return pio;
+}
+
/*
* Function : sata_dwc_exec_command_by_tag
* arguments : ata_port *ap, ata_taskfile *tf, u8 tag, u32 cmd_issued
WBR, Sergei
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