On Fri, 18 Oct 2024, Matt Atwood <matthew.s.atwood@xxxxxxxxx> wrote:
> 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>
> ---
> 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,
No new struct drm_i915_private params or variables please.
BR,
Jani.
> + 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 2743a2dd0a3d..d2775a32bf18 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)
--
Jani Nikula, Intel
