Re: [PATCH 2/2] drm/msm/dsi: don't allow enabling 7nm VCO with unprogrammed rate

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On 12/06/2023 12:21, Marijn Suijten wrote:
On 2023-06-12 11:15:53, Marijn Suijten wrote:
On 2023-06-12 06:16:16, Dmitry Baryshkov wrote:
CCF can try enabling VCO before the rate has been programmed. This can
cause clock lockups and/or other boot issues. Program the VCO to the
minimal PLL rate if the read rate is 0 Hz.

Reported-by: Degdag Mohamed <degdagmohamed@xxxxxxxxx>
Fixes: 1ef7c99d145c ("drm/msm/dsi: add support for 7nm DSI PHY/PLL")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>

This unfortunately regresses my Xperia 5 (sofef01 panel driver that's
on the lists) to now run at 30~33Hz instead of 60Hz.  I can provide
debugging and clk trees later, if needed.

I'll also retest the Xperia 1 with this, which has a 4k DSC panel.

Is this intended to get rid of:

     msm_dsi_phy ae94400.phy: [drm:dsi_pll_7nm_vco_prepare] *ERROR* DSI PLL(0) lock failed, status=0x00000000: -110
     PLL(0) lock failed

... at startup (and relevant rcg2 update_config failures, unbalanced
disables etc)?  It locks after a couple tries but it's still
unnecessarily spammy.

Yes.


- Marijn


- Marijn

---
  drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c | 5 +++++
  1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
index 3b1ed02f644d..6979d35eb7c3 100644
--- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
+++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
@@ -395,11 +395,16 @@ static void dsi_pll_phy_dig_reset(struct dsi_pll_7nm *pll)
  	wmb(); /* Ensure that the reset is deasserted */
  }
+static unsigned long dsi_pll_7nm_vco_recalc_rate(struct clk_hw *hw,
+						  unsigned long parent_rate);
  static int dsi_pll_7nm_vco_prepare(struct clk_hw *hw)
  {
  	struct dsi_pll_7nm *pll_7nm = to_pll_7nm(hw);
  	int rc;
+ if (dsi_pll_7nm_vco_recalc_rate(hw, VCO_REF_CLK_RATE) == 0)
+		dsi_pll_7nm_vco_set_rate(hw, pll_7nm->phy->cfg->min_pll_rate, VCO_REF_CLK_RATE);
+
  	dsi_pll_enable_pll_bias(pll_7nm);
  	if (pll_7nm->slave)
  		dsi_pll_enable_pll_bias(pll_7nm->slave);
--
2.39.2


--
With best wishes
Dmitry




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