On Mon, 29 Jan 2018, Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> wrote:
> On CNL SKUs that uses port F, max DP rate is 8.1G for all
> ports when we have the elevated voltage (higher than 0.85V).
>
> v2: Make commit message more generic.
> v3: Move conditions to a helper to get easier to read. (Ville).
> v4: Add a mention to the numerical voltage on commit
> message per Manasi request.
> v5: Thanks CI! "error: control reaches end of non-void function"
>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Reviewed-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_dp.c | 31 ++++++++++++++++++++++++-------
> 1 file changed, 24 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 86a5e8bfe2a6..1f10bdb855e7 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -220,15 +220,36 @@ intel_dp_downstream_max_dotclock(struct intel_dp *intel_dp)
> return max_dotclk;
> }
>
> +static int cnl_adjusted_max_rate(struct intel_dp *intel_dp, int size)
> +{
> + struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> + struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> + enum port port = dig_port->base.port;
> +
> + u32 voltage = I915_READ(CNL_PORT_COMP_DW3) & VOLTAGE_INFO_MASK;
> +
> + /* Low voltage SKUs are limited to max of 5.4G */
> + if (voltage == VOLTAGE_INFO_0_85V)
> + return size - 2;
> +
> + /* For this SKU 8.1G is supported in all ports */
> + if(IS_CNL_WITH_PORT_F(dev_priv))
> + return size;
> +
> + /* For other SKUs, max rate on ports A and B is 5.4G */
> + if (port == PORT_A || port == PORT_D)
> + return size - 2;
> +
> + return size;
IMO this splits the ARRAY_SIZE() and the (size - 2) adjustments too
much. They were tolerable within one function, but looking at this
function alone, the (size - 2) is a big WTF.
I'd just put this all in the same function.
BR,
Jani.
> +}
> +
> static void
> intel_dp_set_source_rates(struct intel_dp *intel_dp)
> {
> struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> - enum port port = dig_port->base.port;
> const int *source_rates;
> int size;
> - u32 voltage;
>
> /* This should only be done once */
> WARN_ON(intel_dp->source_rates || intel_dp->num_source_rates);
> @@ -238,11 +259,7 @@ intel_dp_set_source_rates(struct intel_dp *intel_dp)
> size = ARRAY_SIZE(bxt_rates);
> } else if (IS_CANNONLAKE(dev_priv)) {
> source_rates = cnl_rates;
> - size = ARRAY_SIZE(cnl_rates);
> - voltage = I915_READ(CNL_PORT_COMP_DW3) & VOLTAGE_INFO_MASK;
> - if (port == PORT_A || port == PORT_D ||
> - voltage == VOLTAGE_INFO_0_85V)
> - size -= 2;
> + size = cnl_adjusted_max_rate(intel_dp, ARRAY_SIZE(cnl_rates));
> } else if (IS_GEN9_BC(dev_priv)) {
> source_rates = skl_rates;
> size = ARRAY_SIZE(skl_rates);
--
Jani Nikula, Intel Open Source Technology Center
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