[Intel-wired-lan] [PATCH iwl-net] ice: fix 'adjust' timer programming for E830 devices

[Simon Horman]

On Thu, Dec 18, 2025 at 10:44:28AM +0100, Grzegorz Nitka wrote:
> Fix incorrect 'adjust the timer' programming sequence for E830 devices
> series. Only shadow registers GLTSYN_SHADJ were programmed in the
> current implementation. According to the specification [1], write to
> command GLTSYN_CMD register is also required with CMD field set to
> "Adjust the Time" value, for the timer adjustment to take the effect.
> 
> The flow was broken for the adjustment less than S32_MAX/MIN range
> (around +/- 2 seconds). For bigger adjustment, non-atomic programming
> flow is used, involving set timer programming. Non-atomic flow is
> implemented correctly.
> 
> Testing hints:
> Run command:
> 	phc_ctl /dev/ptpX get adj 2 get
> Expected result:
> 	Returned timstamps differ at least by 2 seconds
> 
> [1] Intel® Ethernet Controller E830 Datasheet rev 1.3, chapter 9.7.5.4
> https://cdrdv2.intel.com/v1/dl/getContent/787353?explicitVersion=true
> 
> Fixes: f00307522786 ("ice: Implement PTP support for E830 devices")
> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov at intel.com>
> Signed-off-by: Grzegorz Nitka <grzegorz.nitka at intel.com>

Reviewed-by: Simon Horman <horms at kernel.org>