[PATCH 1/2] drm/i915/xe3lpd: Disable HDCP Line Rekeying for Xe3

[Matt Roper]

On Mon, Nov 04, 2024 at 02:01:42PM +0530, Suraj Kandpal wrote:
> We need to disable HDCP Line Rekeying for Xe3 when we are using an HDMI
> encoder. Also remove the Wa comment tag as this follows the bspec and
> does not implement the wa.
> 
> v2: add additional definition instead of function, commit message typo
> fix and update.
> v3: restore lost conditional from v2.
> v4: subject line and subject message updated, fix the if ladder order,
> fix the bit definition order.
> v5: Add the bspec link and remove the Wa comment tag
> v6: Rebase over new changes
> 
> Bspec: 69964
> Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>

I think the code changes are fine now (although you seem to have dropped
the general ladder re-order that was done in v4; was that intentional or
a mistake?), but the subject/commit message seem misleading since the
change this patch is making isn't changing if/when rekeying is disabled,
all it's doing is changing the bit used.  So a commit message more along
the lines of

        drm/i915/xe3lpd: Update HDCP rekying bit

        The TRANS_DDI_FUNC_CTL bit used to enable/disable HDCP rekeying
        has moved from bit 12 (Xe2) to bit 15 (Xe3); update the RMW
        toggle accordingly.

        Also drop the misleading workaround comment tag on this function
        since disabling of HDCP rekeying is something that happens on
        all platforms, not just those impacted by that workaround.

If you decide to reinstate the ladder re-order that you had on an
earlier version of this patch, you could add another sentence like

        While we're here, also re-order the if/else ladder to use
        standard "newest platform first" order.

Anyway, with some kind of commit message cleanup,

        Reviewed-by: Matt Roper <matthew.d.roper at intel.com>


Matt

> ---
>  drivers/gpu/drm/i915/display/intel_hdcp.c | 7 +++++--
>  drivers/gpu/drm/i915/i915_reg.h           | 1 +
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> index f6d42ec6949e..8bca532d1176 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> @@ -31,7 +31,6 @@
>  #define KEY_LOAD_TRIES	5
>  #define HDCP2_LC_RETRY_CNT			3
>  
> -/* WA: 16022217614 */
>  static void
>  intel_hdcp_disable_hdcp_line_rekeying(struct intel_encoder *encoder,
>  				      struct intel_hdcp *hdcp)
> @@ -43,7 +42,11 @@ intel_hdcp_disable_hdcp_line_rekeying(struct intel_encoder *encoder,
>  		return;
>  
>  	if (DISPLAY_VER(display) >= 14) {
> -		if (IS_DISPLAY_VERx100_STEP(display, 1400, STEP_D0, STEP_FOREVER))
> +		if (DISPLAY_VER(display) >= 30)
> +			intel_de_rmw(display,
> +				     TRANS_DDI_FUNC_CTL(display, hdcp->cpu_transcoder),
> +				     0, XE3_TRANS_DDI_HDCP_LINE_REKEY_DISABLE);
> +		else if (IS_DISPLAY_VERx100_STEP(display, 1400, STEP_D0, STEP_FOREVER))
>  			intel_de_rmw(display, MTL_CHICKEN_TRANS(hdcp->cpu_transcoder),
>  				     0, HDCP_LINE_REKEY_DISABLE);
>  		else if (IS_DISPLAY_VERx100_STEP(display, 1401, STEP_B0, STEP_FOREVER) ||
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 22be4a731d27..c160e087972a 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3819,6 +3819,7 @@ enum skl_power_gate {
>  #define  TRANS_DDI_PVSYNC		(1 << 17)
>  #define  TRANS_DDI_PHSYNC		(1 << 16)
>  #define  TRANS_DDI_PORT_SYNC_ENABLE	REG_BIT(15)
> +#define  XE3_TRANS_DDI_HDCP_LINE_REKEY_DISABLE	REG_BIT(15)
>  #define  TRANS_DDI_EDP_INPUT_MASK	(7 << 12)
>  #define  TRANS_DDI_EDP_INPUT_A_ON	(0 << 12)
>  #define  TRANS_DDI_EDP_INPUT_A_ONOFF	(4 << 12)
> -- 
> 2.34.1
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation