[PATCH] libata: Fix a drive detection problem (09c7ad79) · Commits · e / devices / android_kernel_fairphone_FP4

The current code follows the spec but uses an overlong delay. This would be great if the hardware did. Several vendors however forget the D7 pulldown. Fortunately 0xFF isnt a sane reset state so we can use it to skip detection as is done in drivers/ide. (ie this is a tested solution over a long time) Signed-off-by:

Alan Cox <alan@redhat.com> Signed-off-by:

Jeff Garzik <jeff@garzik.org>

drivers/scsi/libata-core.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -2001,9 +2001,19 @@ static unsigned int ata_bus_softreset(struct ata_port *ap,
		* status is checked. Because waiting for "a while" before
		* checking status is fine, post SRST, we perform this magic
		* delay here as well.
		*
		* Old drivers/ide uses the 2mS rule and then waits for ready
		*/
		msleep(150);


		/* Before we perform post reset processing we want to see if
		the bus shows 0xFF because the odd clown forgets the D7 pulldown
		resistor */

		if (ata_check_status(ap) == 0xFF)
		return 1; /* Positive is failure for some reason */

		ata_bus_post_reset(ap, devmask);

		return 0;