Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5270222f authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik
Browse files

libata: don't configure downstream links faster than the upstream link 



There's nothing to be gained by configuring downstream links faster
than the upstream link and such configurations cause problems on
certain PMPs.  Limit downstream link speed by the upstream link speed.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent db64bcf3

drivers/ata/libata-core.c

+16 −6
Original line number Diff line number Diff line
@@ -2751,17 +2751,27 @@ int sata_down_spd_limit(struct ata_link *link) 


static int __sata_set_spd_needed(struct ata_link *link, u32 *scontrol)

{

	u32 spd, limit;

	struct ata_link *host_link = &link->ap->link;

	u32 limit, target, spd;



	if (link->sata_spd_limit == UINT_MAX)

		limit = 0;

	limit = link->sata_spd_limit;



	/* Don't configure downstream link faster than upstream link.

	 * It doesn't speed up anything and some PMPs choke on such

	 * configuration.

	 */

	if (!ata_is_host_link(link) && host_link->sata_spd)

		limit &= (1 << host_link->sata_spd) - 1;



	if (limit == UINT_MAX)

		target = 0;

	else

		limit = fls(link->sata_spd_limit);

		target = fls(limit);



	spd = (*scontrol >> 4) & 0xf;

	*scontrol = (*scontrol & ~0xf0) | ((limit & 0xf) << 4);

	*scontrol = (*scontrol & ~0xf0) | ((target & 0xf) << 4);



	return spd != limit;

	return spd != target;

}



/**