2023-09-12 07:04:29

by claudiu beznea

Subject: [PATCH 08/37] clk: renesas: rzg2l: trust value returned by hardware

From: Claudiu Beznea <[email protected]>

Initial value of CPG_PL2SDHI_DSEL bits 0..1 or 4..6 is 01b. Hardware user's
manual (r01uh0914ej0130-rzg2l-rzg2lc.pdf) specifies that setting 0 is
prohibited. The rzg2l_cpg_sd_clk_mux_get_parent() should just read
CPG_PL2SDHI_DSEL, trust the value and return the proper clock parent index
based on the read value. Do this.

Fixes: eaff33646f4cb ("clk: renesas: rzg2l: Add SDHI clk mux support")
Signed-off-by: Claudiu Beznea <[email protected]>
---
drivers/clk/renesas/rzg2l-cpg.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/clk/renesas/rzg2l-cpg.c b/drivers/clk/renesas/rzg2l-cpg.c
index 1195d4b1f545..d0d086d6dc51 100644
--- a/drivers/clk/renesas/rzg2l-cpg.c
+++ b/drivers/clk/renesas/rzg2l-cpg.c
@@ -239,14 +239,8 @@ static u8 rzg2l_cpg_sd_clk_mux_get_parent(struct clk_hw *hw)

val >>= GET_SHIFT(hwdata->conf);
val &= GENMASK(GET_WIDTH(hwdata->conf) - 1, 0);
- if (val) {
- val--;
- } else {
- /* Prohibited clk source, change it to 533 MHz(reset value) */
- rzg2l_cpg_sd_clk_mux_set_parent(hw, 0);
- }

- return val;
+ return val ? --val : val;
}

static const struct clk_ops rzg2l_cpg_sd_clk_mux_ops = {
--
2.39.2

2023-09-12 16:47:30

by Sergey Shtylyov

Subject: Re: [PATCH 08/37] clk: renesas: rzg2l: trust value returned by hardware

On 9/12/23 7:51 AM, Claudiu wrote:

> From: Claudiu Beznea <[email protected]>
>
> Initial value of CPG_PL2SDHI_DSEL bits 0..1 or 4..6 is 01b. Hardware user's
> manual (r01uh0914ej0130-rzg2l-rzg2lc.pdf) specifies that setting 0 is
> prohibited. The rzg2l_cpg_sd_clk_mux_get_parent() should just read
> CPG_PL2SDHI_DSEL, trust the value and return the proper clock parent index
> based on the read value. Do this.
>
> Fixes: eaff33646f4cb ("clk: renesas: rzg2l: Add SDHI clk mux support")
> Signed-off-by: Claudiu Beznea <[email protected]>
> ---
> drivers/clk/renesas/rzg2l-cpg.c | 8 +-------
> 1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/drivers/clk/renesas/rzg2l-cpg.c b/drivers/clk/renesas/rzg2l-cpg.c
> index 1195d4b1f545..d0d086d6dc51 100644
> --- a/drivers/clk/renesas/rzg2l-cpg.c
> +++ b/drivers/clk/renesas/rzg2l-cpg.c
> @@ -239,14 +239,8 @@ static u8 rzg2l_cpg_sd_clk_mux_get_parent(struct clk_hw *hw)
>
> val >>= GET_SHIFT(hwdata->conf);
> val &= GENMASK(GET_WIDTH(hwdata->conf) - 1, 0);
> - if (val) {
> - val--;
> - } else {
> - /* Prohibited clk source, change it to 533 MHz(reset value) */
> - rzg2l_cpg_sd_clk_mux_set_parent(hw, 0);
> - }
>
> - return val;
> + return val ? --val : val;

return val ? val - 1 : 0;

2023-09-14 15:14:11

by Geert Uytterhoeven

Subject: Re: [PATCH 08/37] clk: renesas: rzg2l: trust value returned by hardware

On Tue, Sep 12, 2023 at 6:43 PM Sergey Shtylyov <[email protected]> wrote:
> On 9/12/23 7:51 AM, Claudiu wrote:
>
> > From: Claudiu Beznea <[email protected]>
> >
> > Initial value of CPG_PL2SDHI_DSEL bits 0..1 or 4..6 is 01b. Hardware user's
> > manual (r01uh0914ej0130-rzg2l-rzg2lc.pdf) specifies that setting 0 is
> > prohibited. The rzg2l_cpg_sd_clk_mux_get_parent() should just read
> > CPG_PL2SDHI_DSEL, trust the value and return the proper clock parent index
> > based on the read value. Do this.
> >
> > Fixes: eaff33646f4cb ("clk: renesas: rzg2l: Add SDHI clk mux support")
> > Signed-off-by: Claudiu Beznea <[email protected]>

> > --- a/drivers/clk/renesas/rzg2l-cpg.c
> > +++ b/drivers/clk/renesas/rzg2l-cpg.c
> > @@ -239,14 +239,8 @@ static u8 rzg2l_cpg_sd_clk_mux_get_parent(struct clk_hw *hw)
> >
> > val >>= GET_SHIFT(hwdata->conf);
> > val &= GENMASK(GET_WIDTH(hwdata->conf) - 1, 0);
> > - if (val) {
> > - val--;
> > - } else {
> > - /* Prohibited clk source, change it to 533 MHz(reset value) */
> > - rzg2l_cpg_sd_clk_mux_set_parent(hw, 0);
> > - }
> >
> > - return val;
> > + return val ? --val : val;
>
> return val ? val - 1 : 0;

Definitely, mixing multiple users of the same variable and pre-decrement
is ill-defined.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds