Quoting Clint Taylor (2024-10-25 17:47:42-03:00) >From: Mika Kahola <mika.kahola@xxxxxxxxx> > >There is a HW issue that arises when there are race conditions >between TCSS entering/exiting TC7 or TC10 states while the >driver is asserting/deasserting TCSS power request. As a >workaround, Display driver will implement a mailbox sequence >to ensure that the TCSS is in TC0 when TCSS power request is >asserted/deasserted. > >The sequence is the following > >1. Read mailbox command status and wait until run/busy bit is > clear >2. Write mailbox data value '1' for power request asserting > and '0' for power request deasserting >3. Write mailbox command run/busy bit and command value with 0x1 >4. Read mailbox command and wait until run/busy bit is clear > before continuing power request. > >Signed-off-by: Mika Kahola <mika.kahola@xxxxxxxxx> >Signed-off-by: Matt Atwood <matthew.s.atwood@xxxxxxxxx> >Signed-off-by: Clint Taylor <Clinton.A.Taylor@xxxxxxxxx> +Mika Mika has sent an updated version on this and it is available at https://lore.kernel.org/intel-gfx/20241028125835.78639-1-mika.kahola@xxxxxxxxx/ I think he might send a new version of that patch based on review feedback. -- Gustavo Sousa >--- > drivers/gpu/drm/i915/display/intel_tc.c | 40 +++++++++++++++++++++++++ > drivers/gpu/drm/i915/i915_reg.h | 7 +++++ > 2 files changed, 47 insertions(+) > >diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c >index 6f2ee7dbc43b..7d9f87db381c 100644 >--- a/drivers/gpu/drm/i915/display/intel_tc.c >+++ b/drivers/gpu/drm/i915/display/intel_tc.c >@@ -1013,6 +1013,39 @@ xelpdp_tc_phy_wait_for_tcss_power(struct intel_tc_port *tc, bool enabled) > return true; > } > >+static bool xelpdp_tc_phy_wait_for_tcss_ready(struct drm_i915_private *i915, >+ bool enable) >+{ >+ if (DISPLAY_VER(i915) < 30) >+ return true; >+ >+ /* check if mailbox is running busy */ >+ if (intel_de_wait_for_clear(i915, TCSS_DISP_MAILBOX_IN_CMD, >+ TCSS_DISP_MAILBOX_IN_CMD_RUN_BUSY, 10)) { >+ drm_dbg_kms(&i915->drm, >+ "timeout waiting for TCSS mailbox run/busy bit to clear\n"); >+ return false; >+ } >+ >+ if (enable) >+ intel_de_write(i915, TCSS_DISP_MAILBOX_IN_DATA, 1); >+ else >+ intel_de_write(i915, TCSS_DISP_MAILBOX_IN_DATA, 0); >+ >+ intel_de_write(i915, TCSS_DISP_MAILBOX_IN_CMD, >+ TCSS_DISP_MAILBOX_IN_CMD_DATA(1)); >+ >+ /* wait to clear mailbox running busy bit before continuing */ >+ if (intel_de_wait_for_clear(i915, TCSS_DISP_MAILBOX_IN_CMD, >+ TCSS_DISP_MAILBOX_IN_CMD_RUN_BUSY, 10)) { >+ drm_dbg_kms(&i915->drm, >+ "timeout waiting for TCSS mailbox run/busy bit to clear\n"); >+ return false; >+ } >+ >+ return true; >+} >+ > static void __xelpdp_tc_phy_enable_tcss_power(struct intel_tc_port *tc, bool enable) > { > struct drm_i915_private *i915 = tc_to_i915(tc); >@@ -1022,6 +1055,13 @@ static void __xelpdp_tc_phy_enable_tcss_power(struct intel_tc_port *tc, bool ena > > assert_tc_cold_blocked(tc); > >+ /* >+ * Gfx driver workaround for PTL tcss_rxdetect_clkswb_req/ack handshake >+ * violation when pwwreq= 0->1 during TC7/10 entry >+ */ >+ drm_WARN_ON(&i915->drm, >+ !xelpdp_tc_phy_wait_for_tcss_ready(i915, enable)); >+ > val = intel_de_read(i915, reg); > if (enable) > val |= XELPDP_TCSS_POWER_REQUEST; >diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h >index 8d758947f301..452325c7f427 100644 >--- a/drivers/gpu/drm/i915/i915_reg.h >+++ b/drivers/gpu/drm/i915/i915_reg.h >@@ -4539,6 +4539,13 @@ enum skl_power_gate { > #define TCSS_DDI_STATUS_HPD_LIVE_STATUS_TBT REG_BIT(1) > #define TCSS_DDI_STATUS_HPD_LIVE_STATUS_ALT REG_BIT(0) > >+#define TCSS_DISP_MAILBOX_IN_CMD _MMIO(0x161300) >+#define TCSS_DISP_MAILBOX_IN_CMD_RUN_BUSY REG_BIT(31) >+#define TCSS_DISP_MAILBOX_IN_CMD_CMD_MASK REG_GENMASK(7, 0) >+#define TCSS_DISP_MAILBOX_IN_CMD_DATA(x) TCSS_DISP_MAILBOX_IN_CMD_RUN_BUSY | \ >+ REG_FIELD_PREP(TCSS_DISP_MAILBOX_IN_CMD_CMD_MASK, (x)) >+#define TCSS_DISP_MAILBOX_IN_DATA _MMIO(0x161304) >+ > #define PRIMARY_SPI_TRIGGER _MMIO(0x102040) > #define PRIMARY_SPI_ADDRESS _MMIO(0x102080) > #define PRIMARY_SPI_REGIONID _MMIO(0x102084) >-- >2.25.1 >
