[v2,2/3] clk: xilinx: vcu: don't set pll_ref as parent of VCU(enc/dec) clocks

Commit Message

Visavalia, Rohit Jan. 2, 2025, 5:03 p.m. UTC

CCF will try to adjust parent clock to set desire clock frequency of
child clock. So if pll_ref is not a fixed-clock then while setting rate
of enc/dec clocks pll_ref may get change, which may make VCU malfunction.

Signed-off-by: Rohit Visavalia <[e-mail]>
---
Changes in v2:
  - none
  - Link to v1: https://lore.kernel.org/linux-clk/[e-mail]
---
 drivers/clk/xilinx/xlnx_vcu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Geert Uytterhoeven Jan. 2, 2025, 7:28 p.m. UTC | #1

Hi Rohit,

On Thu, Jan 2, 2025 at 6:04 PM Rohit Visavalia <[e-mail]> wrote:
> CCF will try to adjust parent clock to set desire clock frequency of
> child clock. So if pll_ref is not a fixed-clock then while setting rate
> of enc/dec clocks pll_ref may get change, which may make VCU malfunction.
>
> Signed-off-by: Rohit Visavalia <[e-mail]>
> ---
> Changes in v2:
>   - none
>   - Link to v1: https://lore.kernel.org/linux-clk/[e-mail]
> ---
>  drivers/clk/xilinx/xlnx_vcu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/clk/xilinx/xlnx_vcu.c b/drivers/clk/xilinx/xlnx_vcu.c
> index 88b3fd8250c2..c520ae1ba65e 100644
> --- a/drivers/clk/xilinx/xlnx_vcu.c
> +++ b/drivers/clk/xilinx/xlnx_vcu.c
> @@ -547,7 +547,7 @@ static int xvcu_register_clock_provider(struct xvcu_device *xvcu)
>                 return PTR_ERR(hw);
>         xvcu->pll_post = hw;
>
> -       parent_data[0].fw_name = "pll_ref";
> +       parent_data[0].fw_name = "dummy_name";
>         parent_data[1].hw = xvcu->pll_post;
>
>         hws[CLK_XVCU_ENC_CORE] =

You completely ignored Stephen's comment, which suggests to not pas
CLK_SET_RATE_PARENT instead (see xvcu_clk_hw_register_leaf()).

Gr{oetje,eeting}s,

                        Geert

Patch

diff --git a/drivers/clk/xilinx/xlnx_vcu.c b/drivers/clk/xilinx/xlnx_vcu.c
index 88b3fd8250c2..c520ae1ba65e 100644
--- a/drivers/clk/xilinx/xlnx_vcu.c
+++ b/drivers/clk/xilinx/xlnx_vcu.c
@@ -547,7 +547,7 @@  static int xvcu_register_clock_provider(struct xvcu_device *xvcu)
 		return PTR_ERR(hw);
 	xvcu->pll_post = hw;
 
-	parent_data[0].fw_name = "pll_ref";
+	parent_data[0].fw_name = "dummy_name";
 	parent_data[1].hw = xvcu->pll_post;
 
 	hws[CLK_XVCU_ENC_CORE] =