Re: [PATCH v2 0/3] scsi: libsas: handle linkrate change in sas_rediscover_dev

[John Garry]

On 13/05/2026 03:16, Xingui Yang wrote:
> When a device attached to an expander phy experiences a linkrate change
> (e.g., due to cable reconnection or negotiation), the current code in
> sas_rediscover_dev() treats it as "broadcast flutter" and takes no action
> if the SAS address and device type remain unchanged.

Can sas_rediscover_dev() check the linkrate (vs expected) to understand 
that this flutter has renegotiated the linkrate and then consider it not 
just a flutter?

> However, for drivers like hisi_sas, the ITCT entry needs to be updated
> to reflect the new linkrate. Without this update, the hardware continues
> using stale linkrate information, which can cause performance issues or
> protocol errors.
>
> This series introduces a new LLDD callback lldd_dev_info_update() to
> notify the low-level driver when a device's information changes, allowing
> the driver to update its hardware structures accordingly. The callback
> is designed to be extensible for future device information updates beyond
> linkrate changes.
>
> Changes from v1:
> - Split into three patches.
>
> Xingui Yang (3):
>    scsi: libsas: refactor sas_ex_to_ata() using new helper
>      sas_ex_to_dev()
>    scsi: libsas: add lldd_dev_info_update callback for device info
>      changes
>    scsi: hisi_sas: add support for dev info update notification
>
>   drivers/scsi/hisi_sas/hisi_sas_main.c | 16 ++++++++++++++++
>   drivers/scsi/libsas/sas_discover.c    | 12 ++++++++++++
>   drivers/scsi/libsas/sas_expander.c    | 25 +++++++++++++++++++------
>   drivers/scsi/libsas/sas_internal.h    |  2 ++
>   include/scsi/libsas.h                 |  1 +
>   5 files changed, 50 insertions(+), 6 deletions(-)