[Skiboot] [PATCH] capi: Add a comment for the Transport Control Register
Andrew Donnellan
andrew.donnellan at au1.ibm.com
Mon May 21 14:53:20 AEST 2018
On 17/05/18 23:16, Christophe Lombard wrote:
> 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.
>
> A new comment is added in the code to avoid confusion and to precise
> the feature of this register.
>
> Signed-off-by: Christophe Lombard <clombard at linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>
> ---
> hw/phb4.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/hw/phb4.c b/hw/phb4.c
> index 18e1e0f..ae584d6 100644
> --- a/hw/phb4.c
> +++ b/hw/phb4.c
> @@ -3764,7 +3764,11 @@ static void phb4_init_capp_regs(struct phb4 *p, uint32_t capp_eng)
> }
> xscom_write(p->chip_id, TRANSPORT_CONTROL + offset, reg);
>
> - /* Initialize CI Store Buffers */
> + /* 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.
> + */
> xscom_read(p->chip_id, TRANSPORT_CONTROL + offset, ®);
> reg |= PPC_BIT(63);
> xscom_write(p->chip_id, TRANSPORT_CONTROL + offset, reg);
>
--
Andrew Donnellan OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com IBM Australia Limited
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