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

[Degdag Mohamed]

[Dmitry Baryshkov],

Thank you for sharing the patches. I have reviewed and tested all
three patches, and they seem to be working correctly.

Tested-by: Degdag Mohamed degdagmohamed at gmail.com

Please let me know if you need any further information or assistance.

Best regards,
Degdag Mohamed

On 6/12/23, Dmitry Baryshkov <dmitry.baryshkov at linaro.org> 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 at gmail.com>
> Fixes: 1ef7c99d145c ("drm/msm/dsi: add support for 7nm DSI PHY/PLL")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> ---
>  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
>
>