[Skiboot] [RESEND][PATCH] phb4/capp: Update DMA read engines set in APC_FSM_READ_MASK based on link-width

[Frederic Barrat]

Le 10/08/2018 à 11:17, Vaibhav Jain a écrit :
> Commit 47c09cdfe7a3('phb4/capp: Calculate STQ/DMA read engines based
> on link-width for PEC') update the CAPP init sequence by calculating
> the needed STQ/DMA-read engines based on link width and populating it
> in XPEC_NEST_CAPP_CNTL register. This however needs to be synchronized
> with the value set in CAPP APC FSM Read Machine Mask Register.
> 
> Hence this patch update phb4_init_capp_regs() to calculate the link
> width of the stack on PEC2 and populate the same values as previously
> populated in PEC CAPP_CNTL register.
> 
> Cc: stable # v5.7+
> Fixes: 47c09cdfe7a3("phb4/capp: Calculate STQ/DMA read engines based on link-width for PEC")
> Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
> ---

This looks okay and will fix it.
In a future patch, we should really work out a simpler logic though. 
It's Friday night so I may over-simplify it, but it seems the DMA read 
engines count is just shifted differently in the PEC and CAPP registers. 
So we should compute the count of DMA read engines only once and pass it 
along to the CAPP init subroutine.

Reviewed-by: Frederic Barrat <fbarrat at linux.vnet.ibm.com>

   Fred


> Change-log:
> Resend -> Fixed the recipient list for this patch.
> ---
>   hw/phb4.c | 20 +++++++++++++++++---
>   1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/phb4.c b/hw/phb4.c
> index 5e07e2bc..19e9a1ec 100644
> --- a/hw/phb4.c
> +++ b/hw/phb4.c
> @@ -3948,10 +3948,24 @@ static void phb4_init_capp_regs(struct phb4 *p, uint32_t capp_eng)
>   		xscom_write(p->chip_id, XPT_FSM_RMM + offset, reg);
>   	}
>   	if (p->index == CAPP1_PHB_INDEX) {
> -		/* Set 30 Read machines for CAPP Minus 20-27 for DMA */
> -		reg = 0xFFFFF00E00000000;
> -		if (capp_eng & CAPP_MAX_DMA_READ_ENGINES)
> +
> +		if (capp_eng & CAPP_MAX_DMA_READ_ENGINES) {
>   			reg = 0xF000000000000000;
> +		} else {
> +			/* Check if PEC is in x8 or x16 mode */
> +			xscom_read(p->chip_id, XPEC_PCI2_CPLT_CONF1, &reg);
> +			if ((reg & XPEC_PCI2_IOVALID_MASK) ==
> +			    XPEC_PCI2_IOVALID_X16)
> +				/* 0-47 (Read machines) are available for
> +				 * capp use
> +				 */
> +				reg = 0x0000FFFFFFFFFFFFULL;
> +			else
> +				/* Set 30 Read machines for CAPP Minus
> +				 * 20-27 for DMA
> +				 */
> +				reg = 0xFFFFF00E00000000;
> +		}
>   		xscom_write(p->chip_id, APC_FSM_READ_MASK + offset, reg);
>   		xscom_write(p->chip_id, XPT_FSM_RMM + offset, reg);
>   	}
>