On Sun, 28 Oct 2007 06:29:32 -0400, Jeff Garzik wrote:
> BTW, looking at the Promise code I see
>
> > cam_con.h:
> > /* for ASIC bug, limit the last element of SG byteCount must < 32 Dword */
> > #define SG_COUNT_ASIC_BUG 32
> > //#define SG_COUNT_ASIC_BUG 128
>
> and in the code itself
>
> > /* check PRD table, last element <= (32 Dword), fix ASIC bug */
>
> (though the code obviously uses SG_COUNT_ASIC_BUG==32, as the first
> paste indicates)
>
> so it seems like Promise first used 128 (32 dwords), but then backed
> down to 32 (8 dwords).
>
> Either way, we definitely have an ASIC bug to work around, it seems...
You're looking at the old pdc-ultra2 driver. The newer unified
sataii150-300 driver (v1.01.0.23) upped the value to 41*4.
I've reviewed Alexander's patch, and I'm currently testing it
with the add-on patch below (fix sg_tablesize, code formatting
stuff, fix uninitialised 'addr' in a VPRINTK).
/Mikael
--- linux-2.6.24-rc1/drivers/ata/sata_promise.c.~1~ 2007-10-28
11:58:01.000000000 +0100
+++ linux-2.6.24-rc1/drivers/ata/sata_promise.c 2007-10-28 12:20:53.000000000
+0100
@@ -155,7 +155,7 @@ static struct scsi_host_template pdc_ata
.queuecommand = ata_scsi_queuecmd,
.can_queue = ATA_DEF_QUEUE,
.this_id = ATA_SHT_THIS_ID,
- .sg_tablesize = LIBATA_MAX_PRD,
+ .sg_tablesize = LIBATA_MAX_PRD-1,
.cmd_per_lun = ATA_SHT_CMD_PER_LUN,
.emulated = ATA_SHT_EMULATED,
.use_clustering = ATA_SHT_USE_CLUSTERING,
@@ -542,7 +542,7 @@ static void pdc_fill_sg(struct ata_queue
if (!(qc->flags & ATA_QCFLAG_DMAMAP))
return;
-
+
WARN_ON(qc->__sg == NULL);
WARN_ON(qc->n_elem == 0 && qc->pad_len == 0);
@@ -579,18 +579,15 @@ static void pdc_fill_sg(struct ata_queue
if (len > SG_COUNT_ASIC_BUG) {
u32 addr;
- /* if len < 2*SG_COUNT_ASIC_BUG then last
- segment will be larger than next-to-last.
- Somewhat ugly :(
- */
VPRINTK("Splitting last PRD.\n");
+ addr = le32_to_cpu(ap->prd[idx - 1].addr);
ap->prd[idx - 1].flags_len -=
cpu_to_le32(SG_COUNT_ASIC_BUG);
VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", idx - 1, addr,
SG_COUNT_ASIC_BUG);
-
- addr = le32_to_cpu(ap->prd[idx - 1].addr) + len -
SG_COUNT_ASIC_BUG;
- len = SG_COUNT_ASIC_BUG;
+
+ addr = addr + len - SG_COUNT_ASIC_BUG;
+ len = SG_COUNT_ASIC_BUG;
ap->prd[idx].addr = cpu_to_le32(addr);
ap->prd[idx].flags_len = cpu_to_le32(len);
VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", idx, addr, len);
-
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