RE: [PATCH v1] clk: imx95-blk-ctl: Fix REFCLK rise-fall mismatch on i.MX95
From: Hongxing Zhu
Date: Fri Apr 17 2026 - 05:47:31 EST
> -----Original Message-----
> From: Peng Fan <peng.fan@xxxxxxx>
> Sent: Friday, April 17, 2026 5:22 PM
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>; abelvesa@xxxxxxxxxx;
> mturquette@xxxxxxxxxxxx; sboyd@xxxxxxxxxx; Frank Li <frank.li@xxxxxxx>;
> s.hauer@xxxxxxxxxxxxxx; festevam@xxxxxxxxx
> Cc: linux-clk@xxxxxxxxxxxxxxx; imx@xxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx
> Subject: RE: [PATCH v1] clk: imx95-blk-ctl: Fix REFCLK rise-fall mismatch on
> i.MX95
>
> Hi Richard,
>
> > Subject: [PATCH v1] clk: imx95-blk-ctl: Fix REFCLK rise-fall mismatch
> > on
> > i.MX95
> >
> > When the internal PLL is used as the PCIe reference clock source on
> > i.MX95, a REFCLK rise-fall time mismatch is observed during PCIe Gen1
> > compliance testing with the Lfast IO analyzer.
> >
> > Fix this issue by configuring the IREF_TX field to 0xF (15), which
> > adjusts the transmitter current reference to meet the PCIe
> > specification timing requirements.
>
> BLK CTRL in HSIOMIX should be save/restore for the settings you configured in
> probe phase.
Good suggestion, thanks.
Best Regards
Richard Zhu
>
> Regards
> Peng.
>
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > ---
> > drivers/clk/imx/clk-imx95-blk-ctl.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/clk/imx/clk-imx95-blk-ctl.c
> > b/drivers/clk/imx/clk- imx95-blk-ctl.c index
> > 1f9259f45607..bc6957299cec 100644
> > --- a/drivers/clk/imx/clk-imx95-blk-ctl.c
> > +++ b/drivers/clk/imx/clk-imx95-blk-ctl.c
> > @@ -44,6 +44,8 @@ struct imx95_blk_ctl_clk_dev_data {
> > const char * const *parent_names;
> > u32 num_parents;
> > u32 reg;
> > + u32 reg_init_msk;
> > + u32 reg_init_val;
> > u32 bit_idx;
> > u32 bit_width;
> > u32 clk_type;
> > @@ -289,6 +291,8 @@ static const struct imx95_blk_ctl_clk_dev_data
> > hsio_blk_ctl_clk_dev_data[] = {
> > .parent_names = (const char *[]){ "func_out_en", },
> > .num_parents = 1,
> > .reg = 0,
> > + .reg_init_msk = GENMASK(10, 7),
> > + .reg_init_val = GENMASK(10, 7),
> > .bit_idx = 6,
> > .bit_width = 1,
> > .type = CLK_GATE,
> > @@ -410,6 +414,9 @@ static int imx95_bc_probe(struct platform_device
> > *pdev)
> > const struct imx95_blk_ctl_clk_dev_data *data = &bc-
> > >pdata->clk_dev_data[i];
> > void __iomem *reg = base + data->reg;
> >
> > + if (data->reg_init_msk)
> > + writel((readl(reg) & ~data->reg_init_msk) |
> > data->reg_init_val,
> > +reg);
> > +
> > if (data->type == CLK_MUX) {
> > hws[i] = clk_hw_register_mux(dev, data-
> > >name, data->parent_names,
> > data-
> > >num_parents, data->flags, reg,
> > --
> > 2.37.1