From 5270222f96608818e431b5c4029b1f12020ab719 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 31 Oct 2007 10:17:07 +0900 Subject: [PATCH] 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: Tejun Heo Signed-off-by: Jeff Garzik --- drivers/ata/libata-core.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 3a1ec4e715e..164c7d9514f 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -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; } /** -- 2.41.1