Author: ian
Date: Sat Feb 15 17:59:32 2014
New Revision: 261940
URL: http://svnweb.freebsd.org/changeset/base/261940
Log:
Increase the wait time for acquiring the bus from 10 to 250ms.
Normally it never needs to wait here at all; waiting is done at the end
of the prior command. When doing a crash dump, the normal interrupt
mechanism isn't used; instead the interrupt handler is called repeatedly
in a polling-like manner. This can subvert hardware-specific drivers
and lead to trying to start a new command while the previous command is
still busy on the bus. Since the SD spec says the longest a card can
take to execute any command is 250ms, use that as a timeout.
Modified:
head/sys/dev/sdhci/sdhci.c
Modified: head/sys/dev/sdhci/sdhci.c
==============================================================================
--- head/sys/dev/sdhci/sdhci.c Sat Feb 15 17:55:35 2014 (r261939)
+++ head/sys/dev/sdhci/sdhci.c Sat Feb 15 17:59:32 2014 (r261940)
@@ -767,8 +767,17 @@ sdhci_start_command(struct sdhci_slot *s
/* We shouldn't wait for DAT for stop commands. */
if (cmd == slot->req->stop)
mask &= ~SDHCI_DAT_INHIBIT;
- /* Wait for bus no more then 10 ms. */
- timeout = 10;
+ /*
+ * Wait for bus no more then 250 ms. Typically there will be no wait
+ * here at all, but when writing a crash dump we may be bypassing the
+ * host platform's interrupt handler, and in some cases that handler
+ * may be working around hardware quirks such as not respecting r1b
+ * busy indications. In those cases, this wait-loop serves the purpose
+ * of waiting for the prior command and data transfers to be done, and
+ * SD cards are allowed to take up to 250ms for write and erase ops.
+ * (It's usually more like 20-30ms in the real world.)
+ */
+ timeout = 250;
while (state & mask) {
if (timeout == 0) {
slot_printf(slot, "Controller never released "
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