sata_svw: check DMA start bit before reset
authorDavid Milburn <dmilburn@redhat.com>
Mon, 29 Oct 2012 23:00:22 +0000 (18:00 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 3 Dec 2012 19:47:11 +0000 (11:47 -0800)
commit08ecfb7dd2e41f8aa9bd57468e09fdc5bbbc2ec6
tree863a1c125d50c4b68675ef2a1a0a194b0fa20e2a
parent65c03b4c0598a71e125a96985f5a402347f7ffb3
sata_svw: check DMA start bit before reset

commit b03e66a6be91f8389fcd902ab6c1563db1c9c06b upstream.

If kdump is triggered with pending IO, controller may not respond causing
kdump to fail.

http://marc.info/?l=linux-ide&m=133032255424658&w=2

During error recovery ata_do_dev_read_id never completes due hang
in mmio_insw.

ata_do_dev_read_id
 ata_sff_data_xfer
  ioread16_rep
   mmio_insw

if DMA start bit is cleared before reset, PIO command is successful
and kdump succeeds.

Signed-off-by: David Milburn <dmilburn@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Cc: CAI Qian <caiqian@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/ata/sata_svw.c