[Skiboot] [PATCH] phb4: Minor CAPP init cleanup

[christophe lombard]

Le 23/04/2018 à 07:41, Michael Neuling a écrit :
> Currently we RMW the TRANSPORT_CONTROL register and then RMW it again
> for no good reason. Make this a single RMW.
> 
> Signed-off-by: Michael Neuling <mikey at neuling.org>
> ---
>   hw/phb4.c | 3 ---
>   1 file changed, 3 deletions(-)
> 
> diff --git a/hw/phb4.c b/hw/phb4.c
> index 50e1be1c4c..134d1747b5 100644
> --- a/hw/phb4.c
> +++ b/hw/phb4.c
> @@ -3756,10 +3756,7 @@ static void phb4_init_capp_regs(struct phb4 *p, uint32_t capp_eng)
>   			reg |= PPC_BIT(60);
>   		}
>   	}
> -	xscom_write(p->chip_id, TRANSPORT_CONTROL + offset, reg);
> -
>   	/* Initialize CI Store Buffers */
> -	xscom_read(p->chip_id, TRANSPORT_CONTROL + offset, &reg);
>   	reg |= PPC_BIT(63);
>   	xscom_write(p->chip_id, TRANSPORT_CONTROL + offset, reg);
> 

Hi Mikey

As Nicholas Ollerich pointed out during the bringup of capi2, the 
transport control register needs to be loaded in two steps.
Once the register values have been set, we have to write bit 63 to a 
'1', which loads the register values into the ci store buffer logic.
Bit 63 always reads back as a zero but to load the ci store buffer 
values in capp the transition of 0 to 1 of bit 63 must be seen.

Thanks,

Christophe