diff mbox series

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

Message ID 20230912045157.177966-9-claudiu.beznea.uj@bp.renesas.com
State Superseded
Headers show
Series [01/37] dt-bindings: serial: renesas,scif: document r9a08g045 support | expand

Commit Message

Claudiu Sept. 12, 2023, 4:51 a.m. UTC 
From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

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 <claudiu.beznea.uj@bp.renesas.com>
---
 drivers/clk/renesas/rzg2l-cpg.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

Comments

Geert Uytterhoeven Sept. 14, 2023, 12:18 p.m. UTC | #1 
On Tue, Sep 12, 2023 at 6:43 PM Sergey Shtylyov <s.shtylyov@omp.ru> wrote:
> On 9/12/23 7:51 AM, Claudiu wrote:
>
> > From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >
> > 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 <claudiu.beznea.uj@bp.renesas.com>

> > --- 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
diff mbox series

Patch

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 = {