On 10/09/2024, Marek Vasut wrote:
> The media_ldb_root_clk supply LDB serializer. These clock are usually
> shared with the LCDIFv3 pixel clock and supplied by the Video PLL on
> i.MX8MP, but the LDB clock run at either x7 or x14 rate of the LCDIFv3
> pixel clock. Allow the LDB to reconfigure Video PLL as needed, as that
> results in accurate serializer clock.
> 
> Signed-off-by: Marek Vasut <[email protected]>
> ---
> Cc: Abel Vesa <[email protected]>
> Cc: Andrzej Hajda <[email protected]>
> Cc: David Airlie <[email protected]>
> Cc: Fabio Estevam <[email protected]>
> Cc: Isaac Scott <[email protected]>
> Cc: Jernej Skrabec <[email protected]>
> Cc: Jonas Karlman <[email protected]>
> Cc: Laurent Pinchart <[email protected]>
> Cc: Maarten Lankhorst <[email protected]>
> Cc: Maxime Ripard <[email protected]>
> Cc: Michael Turquette <[email protected]>
> Cc: Neil Armstrong <[email protected]>
> Cc: Peng Fan <[email protected]>
> Cc: Pengutronix Kernel Team <[email protected]>
> Cc: Robert Foss <[email protected]>
> Cc: Sascha Hauer <[email protected]>
> Cc: Shawn Guo <[email protected]>
> Cc: Simona Vetter <[email protected]>
> Cc: Stephen Boyd <[email protected]>
> Cc: Thomas Zimmermann <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
>  drivers/clk/imx/clk-imx8mp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/imx/clk-imx8mp.c b/drivers/clk/imx/clk-imx8mp.c
> index 516dbd170c8a3..2e61d340b8ab7 100644
> --- a/drivers/clk/imx/clk-imx8mp.c
> +++ b/drivers/clk/imx/clk-imx8mp.c
> @@ -611,7 +611,7 @@ static int imx8mp_clocks_probe(struct platform_device 
> *pdev)
>       hws[IMX8MP_CLK_MEDIA_MIPI_PHY1_REF] = 
> imx8m_clk_hw_composite("media_mipi_phy1_ref", 
> imx8mp_media_mipi_phy1_ref_sels, ccm_base + 0xbd80);
>       hws[IMX8MP_CLK_MEDIA_DISP1_PIX] = 
> imx8m_clk_hw_composite_bus_flags("media_disp1_pix", 
> imx8mp_media_disp_pix_sels, ccm_base + 0xbe00, CLK_SET_RATE_PARENT);
>       hws[IMX8MP_CLK_MEDIA_CAM2_PIX] = 
> imx8m_clk_hw_composite("media_cam2_pix", imx8mp_media_cam2_pix_sels, ccm_base 
> + 0xbe80);
> -     hws[IMX8MP_CLK_MEDIA_LDB] = imx8m_clk_hw_composite("media_ldb", 
> imx8mp_media_ldb_sels, ccm_base + 0xbf00);
> +     hws[IMX8MP_CLK_MEDIA_LDB] = 
> imx8m_clk_hw_composite_bus_flags("media_ldb", imx8mp_media_ldb_sels, ccm_base 
> + 0xbf00, CLK_SET_RATE_PARENT);

This patch would cause the below in-flight LDB bridge driver
patch[1] fail to do display mode validation upon display modes
read from LVDS to HDMI converter IT6263's DDC I2C bus.
Unsupported display modes cannot be ruled out.  Note that
"media_ldb" is derived from "video_pll1_out" by default as the
parent is set in imx8mp.dtsi.  And, the only 4 rates supported
by "video_pll1" are listed in imx_pll1443x_tbl[] - 1.0395GHz,
650MHz, 594MHz and 519.75MHz.

[1] https://patchwork.freedesktop.org/patch/616907/?series=139266&rev=1

>       hws[IMX8MP_CLK_MEMREPAIR] = 
> imx8m_clk_hw_composite_critical("mem_repair", imx8mp_memrepair_sels, ccm_base 
> + 0xbf80);
>       hws[IMX8MP_CLK_MEDIA_MIPI_TEST_BYTE] = 
> imx8m_clk_hw_composite("media_mipi_test_byte", 
> imx8mp_media_mipi_test_byte_sels, ccm_base + 0xc100);
>       hws[IMX8MP_CLK_ECSPI3] = imx8m_clk_hw_composite("ecspi3", 
> imx8mp_ecspi3_sels, ccm_base + 0xc180);

-- 
Regards,
Liu Ying

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