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

[pandora-kernel.git] / drivers / ata / libata-core.c

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 3a1ec4e..164c7d9 100644 (file)
--- 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;
 }
 
 /**