From: Tejun Heo Date: Wed, 31 Oct 2007 01:17:07 +0000 (+0900) Subject: libata: don't configure downstream links faster than the upstream link X-Git-Tag: v2.6.24-rc2~48^2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5270222f96608818e431b5c4029b1f12020ab719;p=linux-2.6 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 --- diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 3a1ec4e715..164c7d9514 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; } /**