[Skiboot] [PATCH v2] phb4/capp: Calculate STQ/DMA read engines based on link-width for PEC

[christophe lombard]

Le 04/07/2018 à 17:01, Vaibhav Jain a écrit :
> Presently in CAPI mode the number of STQ/DMA-read engines allocated on
> PEC2 for CAPP is fixed to 6 and 0-30 respectively irrespective of the
> PCI link width. These values are only suitable for x8 cards and
> quickly run out if a x16 card is plugged to a PEC2 attached slot. This
> usually manifests as CAPP reporting TLBI timeout due to these messages
> getting stalled due to insufficient STQs.
> 
> To fix this we update enable_capi_mode() to check if PEC2 chiplet is
> in x16 mode and if yes then we allocate 4/0-47 STQ/DMA-read engines
> for the CAPP traffic.
> 
> Cc: stable # v5.7+
> Fixes: 37ea3cfdc852("capi: Enable capi mode for PHB4")
> Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>
> Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
> ---
> Change-log:
> v2 ->	Updated code comment to mention DMA read machines
>     	enabled. [Andrew]
> 	Marked the patch for stable inclusion [Andrew]
> ---
>   hw/phb4.c           | 36 +++++++++++++++++++++++++++---------
>   include/phb4-regs.h |  6 ++++++
>   2 files changed, 33 insertions(+), 9 deletions(-)
> 

Thanks.

Reviewed-by: Christophe Lombard <clombard at linux.vnet.ibm.com>