During hotplug, it is possible for 6Gbps link speed to be limited all the way down to 1.5 Gbps which may lead to a slower link speed when drive is re-connected. This behavior has been seen on a Intel Lewisburg SATA controller (8086:a1d2) with HGST HUH728080ALE600 drive where SATA link speed was limited to 1.5 Gbps and when re-connected the link came up 3.0 Gbps. This patch was retested on above configuration and showed the hotplugged link to come back online at max speed (6Gbps). I did not see the downgrade when testing on Intel C600/X79, but retested patched linux-4.14-rc5 kernel and didn't see any side effects from this change. Also, successfully retested hotplug on port multiplier 3Gbps link. Signed-off-by: David Milburn <dmilburn@xxxxxxxxxx> --- drivers/ata/libata-core.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index ee4c1ec..b72b242 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -3081,12 +3081,17 @@ int sata_down_spd_limit(struct ata_link *link, u32 spd_limit) mask &= ~(1 << bit); /* Mask off all speeds higher than or equal to the current - * one. Force 1.5Gbps if current SPD is not available. + * one. At this point if current SPD is not available and we + * previously recorded the link speed from the Status register, + * the driver has already masked off the highest bit so mask + * should already be set to 1 or 0. Otherwise, we should + * not force 1.5Gbps on a link where we have not previously + * recorded speed from Status register, just return in this case. */ if (spd > 1) mask &= (1 << (spd - 1)) - 1; else - mask &= 1; + return -EINVAL; /* were we already at the bottom? */ if (!mask) -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
