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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 <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
hifive-unleashed-5.1
Tejun Heo 2007-10-31 10:17:07 +09:00 committed by Jeff Garzik
parent db64bcf387
commit 5270222f96
1 changed files with 16 additions and 6 deletions
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22
drivers/ata/libata-core.c
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@ -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;
}
/**