On Tue, Jun 16, 2026 at 01:15:53PM +0300, Vinod Govindapillai wrote:
> Bspec has been updated for xe2_lpd+ platforms on how to handle
> the bw buddy prgramming in case no matching memory configuration
> is found w.r.t the current page mask table. The recommendation
> is to keep the default settings for the related registers as it
> is without explicitly disabling the bw buddy.
>
> Bspec: 68871
> Suggested-by: Ville Syrjala <[email protected]>
> Signed-off-by: Vinod Govindapillai <[email protected]>
> ---
> .../drm/i915/display/intel_display_power.c | 43 +++++++++++++------
> 1 file changed, 30 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c
> b/drivers/gpu/drm/i915/display/intel_display_power.c
> index 2e51dfcd5dce..dcfd78f48622 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> @@ -1631,23 +1631,40 @@ static void tgl_bw_buddy_init(struct intel_display
> *display)
> table[config].type == dram_info->type)
> break;
>
> + /*
> + * If we don't recognize the memory configuration, explicitly disable
> + * the address buddy logic in pre-xe2_lpd platforms as it was before.
> + * In xe2_lpd+ cases, page masks must be set to 0 if no matching
> + * configuration is found in the table. So keep the default settings
> + * as it is. By default, BW_BUDDY_CTL bit 31 is 0 (bw buddy enabled)
> + * and BW_BUDDY_PAGE_MASK is 0x0
This seems to mostly just repeat what the code already says.
> + *
> + * TODO: Revisit the buddy page masks table when bspec updates the
> + * table with the correct number of channels for each dram type.
> + */
That TODO is unrelated to the changes here, and also seems misplaced.
> if (table[config].page_mask == 0) {
> drm_dbg_kms(display->drm,
> "Unknown memory configuration; disabling address
> buddy logic.\n");
> - for_each_set_bit(i, &abox_mask, BITS_PER_TYPE(abox_mask))
> - intel_de_write(display, BW_BUDDY_CTL(i),
> - BW_BUDDY_DISABLE);
> - } else {
> - for_each_set_bit(i, &abox_mask, BITS_PER_TYPE(abox_mask)) {
> - intel_de_write(display, BW_BUDDY_PAGE_MASK(i),
> - table[config].page_mask);
> -
> - /* Wa_22010178259:tgl,dg1,rkl,adl-s */
> - if (intel_display_wa(display,
> INTEL_DISPLAY_WA_22010178259))
> - intel_de_rmw(display, BW_BUDDY_CTL(i),
> - BW_BUDDY_TLB_REQ_TIMER_MASK,
> - BW_BUDDY_TLB_REQ_TIMER(0x8));
> +
> + if (DISPLAY_VER(display) < 20) {
> + for_each_set_bit(i, &abox_mask,
> BITS_PER_TYPE(abox_mask))
> + intel_de_write(display, BW_BUDDY_CTL(i),
> + BW_BUDDY_DISABLE);
> }
> +
> + return;
> + }
> +
> + /* We found a matching configuration. Program the BW_BUDDY registers. */
Seems obvious. The comment is redundant.
> + for_each_set_bit(i, &abox_mask, BITS_PER_TYPE(abox_mask)) {
> + intel_de_write(display, BW_BUDDY_PAGE_MASK(i),
> + table[config].page_mask);
Please split code restructuring from functional changes. This diff
is too hard to read.
> +
> + /* Wa_22010178259:tgl,dg1,rkl,adl-s */
> + if (intel_display_wa(display, INTEL_DISPLAY_WA_22010178259))
> + intel_de_rmw(display, BW_BUDDY_CTL(i),
> + BW_BUDDY_TLB_REQ_TIMER_MASK,
> + BW_BUDDY_TLB_REQ_TIMER(0x8));
> }
> }
>
> --
> 2.43.0
--
Ville Syrjälä
Intel
