[Skiboot] [PATCH 2/3] npu2-hw-procedures: Fix zcal in mixed opencapi and nvlink mode

[Andrew Donnellan]

On 16/3/19 3:44 am, Frederic Barrat wrote:
> The zcal procedure needs to be run once per obus. We keep track of
> which obus is already calibrated in an array indexed by the obus
> number. However, the obus number is inferred from the brick index,
> which works well for nvlink but not for opencapi.
> 
> Create an obus_index() function, which, from a device, returns the
> correct obus index, irrespective of the device type.
> 
> Signed-off-by: Frederic Barrat <fbarrat at linux.ibm.com>

Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

> ---
>   hw/npu2-hw-procedures.c | 24 +++++++++++++++++++++---
>   1 file changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/npu2-hw-procedures.c b/hw/npu2-hw-procedures.c
> index 3ee646cd..2f330957 100644
> --- a/hw/npu2-hw-procedures.c
> +++ b/hw/npu2-hw-procedures.c
> @@ -201,11 +201,29 @@ static uint32_t nop(struct npu2_dev *npu_dev __unused)
>   }
>   DEFINE_PROCEDURE(nop);
>   
> -/* Return the brick number (0-2) within an obus chiplet */
> +/*
> + * Return the obus (0 or 1) of a device
> + *
> + * Using the brick index is dangerous, because it varies for a link
> + * depending on the mode (opencapi or nvlink)
> + */
> +static int obus_index(struct npu2_dev *ndev)
> +{
> +	if ((ndev->pl_xscom_base & 0x3F000000) == 0x09000000)
> +		return 0;
> +	else
> +		return 1;
> +}
> +
> +/*
> + * Return the brick number (0-2) within an obus chiplet.
> + * Only valid for nvlink devices
> + */
>   static int obus_brick_index(struct npu2_dev *ndev)
>   {
>   	int index = ndev->brick_index % 3;
>   
> +	assert(ndev->type != NPU2_DEV_TYPE_OPENCAPI);
>   	/* On the second obus chiplet, index is reversed */
>   	if ((ndev->pl_xscom_base & 0x3F000000) != 0x09000000)
>   		return 2 - index;
> @@ -441,7 +459,7 @@ DEFINE_PROCEDURE(phy_reset, phy_reset_wait, phy_reset_complete);
>   /* Procedure 1.2.6 - I/O PHY Tx Impedance Calibration */
>   static uint32_t phy_tx_zcal(struct npu2_dev *ndev)
>   {
> -	if (ndev->npu->tx_zcal_complete[ndev->brick_index > 2])
> +	if (ndev->npu->tx_zcal_complete[obus_index(ndev)])
>   		return PROCEDURE_COMPLETE;
>   
>   	/* Turn off SW enable and enable zcal state machine */
> @@ -612,7 +630,7 @@ static uint32_t phy_tx_zcal_calculate(struct npu2_dev *ndev)
>   	phy_write(ndev, &NPU2_PHY_TX_MARGINPU_SELECT, therm(margin_select + 1)/2);
>   	phy_write(ndev, &NPU2_PHY_TX_MARGINPD_SELECT, therm(margin_select + 1)/2);
>   
> -	ndev->npu->tx_zcal_complete[ndev->brick_index > 2] = 1;
> +	ndev->npu->tx_zcal_complete[obus_index(ndev)] = 1;
>   	return PROCEDURE_COMPLETE;
>   }
>   DEFINE_PROCEDURE(phy_tx_zcal, phy_tx_zcal_wait, phy_tx_zcal_calculate);
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited