I tried the patch but it doesn't work for me using an USB-2 Memory stick "DiskonKey" on an USB-2 port (with uhci_hcd & ehci_hcd loaded).
After a 3 minute time-out I get
"SCSI device sda: drive cache: write through"
and the device starts working just fine.Unloading the ehci_hcd module doesn't make any difference. Only when ripping out the whole mode-sense call it works immediately :-) so it appears the device is just unhappy about the sd_do_mode_sense.
_
Regards,
Ruud LindersLinus Torvalds wrote:
On 22 Sep 2003, James Bottomley wrote:
I think we could try 4 bytes for this (even to avoid wide residue problems) and see how it goes.
How about just trusting the size (and as far as I can tell from the SCSI specs, the size is the size _without_ the header and block descriptors), and capping it at 20?
If the device reports a size that is smaller than the required one (3), we just fail the request - instead of doing a small read and then making decisions on data that isn't even there, like we used to do!
(The old code would use the "size" as the read length argument, which really looks fundamentally wrong. At the very least it should add in the header length etc).
Can people try this attached patch? It looks bigger than it is - in order to do sane error handling for the "size is too small" case I re-organized the thing a bit. The real change is just
- capping size at 20 (real value) instead of 128 (random crud) - properly add in the header and block descriptor sizes
Comments?
Linus
-----
===== drivers/scsi/sd.c 1.134 vs edited =====
--- 1.134/drivers/scsi/sd.c Wed Jun 25 04:47:26 2003
+++ edited/drivers/scsi/sd.c Mon Sep 22 12:42:32 2003
@@ -1108,14 +1108,26 @@
/* cautiously ask */
res = sd_do_mode_sense(SRpnt, dbd, modepage, buffer, 4, &data);
- if (scsi_status_is_good(res)) {
- /* that went OK, now ask for the proper length */
- len = data.length;
- if (len > 128)
- len = 128;
- res = sd_do_mode_sense(SRpnt, dbd, modepage, buffer,
- len, &data);
- }
+ if (!scsi_status_is_good(res))
+ goto bad_sense;
+
+ /* that went OK, now ask for the proper length */
+ len = data.length;
+
+ /*
+ * We're only interested in the first three bytes, actually.
+ * But the data cache page is defined for the first 20.
+ */
+ if (len < 3)
+ goto bad_sense;
+ if (len > 20)
+ len = 20;
+
+ /* Take headers and block descriptors into account */
+ len += data.header_length + data.block_descriptor_length;
+
+ /* Get the data */
+ res = sd_do_mode_sense(SRpnt, dbd, modepage, buffer, len, &data);
if (scsi_status_is_good(res)) {
const char *types[] = {
@@ -1133,23 +1145,26 @@
printk(KERN_NOTICE "SCSI device %s: drive cache: %s\n",
diskname, types[ct]);
+
+ return;
+ }
+
+bad_sense:
+ if ((SRpnt->sr_sense_buffer[0] & 0x70) == 0x70
+ && (SRpnt->sr_sense_buffer[2] & 0x0f) == ILLEGAL_REQUEST
+ /* ASC 0x24 ASCQ 0x00: Invalid field in CDB */
+ && SRpnt->sr_sense_buffer[12] == 0x24
+ && SRpnt->sr_sense_buffer[13] == 0x00) {
+ printk(KERN_NOTICE "%s: cache data unavailable\n",
+ diskname);
} else {
- if ((SRpnt->sr_sense_buffer[0] & 0x70) == 0x70
- && (SRpnt->sr_sense_buffer[2] & 0x0f) == ILLEGAL_REQUEST
- /* ASC 0x24 ASCQ 0x00: Invalid field in CDB */
- && SRpnt->sr_sense_buffer[12] == 0x24
- && SRpnt->sr_sense_buffer[13] == 0x00) {
- printk(KERN_NOTICE "%s: cache data unavailable\n",
- diskname);
- } else {
- printk(KERN_ERR "%s: asking for cache data failed\n",
- diskname);
- }
- printk(KERN_ERR "%s: assuming drive cache: write through\n",
+ printk(KERN_ERR "%s: asking for cache data failed\n",
diskname);
- sdkp->WCE = 0;
- sdkp->RCD = 0;
}
+ printk(KERN_ERR "%s: assuming drive cache: write through\n",
+ diskname);
+ sdkp->WCE = 0;
+ sdkp->RCD = 0;
}
/**
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