drm/i915: Tweaked Wa_14010685332 for PCHs used on gen11 platforms
The WA specifies that we need to toggle a SDE chicken bit on and then off as the final step in preparation for s0ix entry. Bspec: 33450 Bspec: 8402 However, something is happening after we toggle the bit that causes the WA to be invalidated. This makes dispcnlunit1_cp_xosc_clkreq active being already in s0ix state i.e SLP_S0 counter incremented. Tweaking the Wa_14010685332 by setting the bit on suspend and clearing it on resume turns down the dispcnlunit1_cp_xosc_clkreq. B.Spec has Documented this tweaked sequence of WA as an alternative. Let keep this tweaked WA for Gen11 platforms and keep untweaked WA for other platforms which never observed this issue. v2 (MattR): - Change the comment on the workaround to give PCH names rather than platform names. Although the bspec is setup to list workarounds by platform, the hardware team has confirmed that the actual issue being worked around here is something that was introduced back in the Cannon Lake PCH and carried forward to subsequent PCH's. - Extend the untweaked version of the workaround to include PCH_CNP as well. Note that since PCH_CNP is used to represent CMP, this will apply on CML and some variants of RKL too. - Cap the untweaked version of the workaround so that it won't apply to "fake" PCH's (i.e., DG1). The issue we're working around really is an issue in the PCH itself, not the South Display, so it shouldn't apply when there isn't a real PCH. v3: - use intel_de_rmw(). [Rodrigo] Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Signed-off-by: Bob Paauwe <bob.j.paauwe@intel.com> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com> Signed-off-by: Matt Roper <matthew.d.roper@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20201110121700.4338-1-anshuman.gupta@intel.comReviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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