From: Alexandre Belloni <alexandre.belloni@bootlin.com> To: Claudiu Beznea <claudiu.beznea@microchip.com> Cc: mturquette@baylibre.com, sboyd@kernel.org, nicolas.ferre@microchip.com, ludovic.desroches@microchip.com, linux-kernel@vger.kernel.org, mturquette@linaro.org, bbrezillon@kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 2/2] clk: at91: main: do not continue if oscillators already prepared Date: Fri, 26 Jun 2020 23:03:57 +0200 [thread overview] Message-ID: <20200626210357.GX131826@piout.net> (raw) In-Reply-To: <1593079768-9349-2-git-send-email-claudiu.beznea@microchip.com> On 25/06/2020 13:09:28+0300, Claudiu Beznea wrote: > Return in clk_main_osc_prepare()/clk_main_rc_osc_prepare() if > oscillators are already enabled. > > Fixes: 27cb1c2083373 ("clk: at91: rework main clk implementation") > Fixes: 1bdf02326b71e ("clk: at91: make use of syscon/regmap internally") Is this really a fix? What is the observed issue? > Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com> > --- > drivers/clk/at91/clk-main.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c > index 37c22667e831..46b4d2131989 100644 > --- a/drivers/clk/at91/clk-main.c > +++ b/drivers/clk/at91/clk-main.c > @@ -74,13 +74,11 @@ static int clk_main_osc_prepare(struct clk_hw *hw) > regmap_read(regmap, AT91_CKGR_MOR, &tmp); > tmp &= ~MOR_KEY_MASK; > > - if (tmp & AT91_PMC_OSCBYPASS) > + if (tmp & (AT91_PMC_OSCBYPASS | AT91_PMC_MOSCEN)) > return 0; While this seems like a good optimization, it is also not correct. Having AT91_PMC_MOSCEN set doesn't mean that the clock is ready, you need to at least check MOSCS once. > > - if (!(tmp & AT91_PMC_MOSCEN)) { > - tmp |= AT91_PMC_MOSCEN | AT91_PMC_KEY; > - regmap_write(regmap, AT91_CKGR_MOR, tmp); > - } > + tmp |= AT91_PMC_MOSCEN | AT91_PMC_KEY; > + regmap_write(regmap, AT91_CKGR_MOR, tmp); > > while (!clk_main_osc_ready(regmap)) > cpu_relax(); > @@ -186,10 +184,12 @@ static int clk_main_rc_osc_prepare(struct clk_hw *hw) > > regmap_read(regmap, AT91_CKGR_MOR, &mor); > > - if (!(mor & AT91_PMC_MOSCRCEN)) > - regmap_update_bits(regmap, AT91_CKGR_MOR, > - MOR_KEY_MASK | AT91_PMC_MOSCRCEN, > - AT91_PMC_MOSCRCEN | AT91_PMC_KEY); > + if (mor & AT91_PMC_MOSCRCEN) > + return 0; > + > + regmap_update_bits(regmap, AT91_CKGR_MOR, > + MOR_KEY_MASK | AT91_PMC_MOSCRCEN, > + AT91_PMC_MOSCRCEN | AT91_PMC_KEY); > > while (!clk_main_rc_osc_ready(regmap)) > cpu_relax(); > -- > 2.7.4 > -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
WARNING: multiple messages have this Message-ID (diff)
From: Alexandre Belloni <alexandre.belloni@bootlin.com> To: Claudiu Beznea <claudiu.beznea@microchip.com> Cc: mturquette@linaro.org, bbrezillon@kernel.org, sboyd@kernel.org, mturquette@baylibre.com, linux-kernel@vger.kernel.org, ludovic.desroches@microchip.com, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 2/2] clk: at91: main: do not continue if oscillators already prepared Date: Fri, 26 Jun 2020 23:03:57 +0200 [thread overview] Message-ID: <20200626210357.GX131826@piout.net> (raw) In-Reply-To: <1593079768-9349-2-git-send-email-claudiu.beznea@microchip.com> On 25/06/2020 13:09:28+0300, Claudiu Beznea wrote: > Return in clk_main_osc_prepare()/clk_main_rc_osc_prepare() if > oscillators are already enabled. > > Fixes: 27cb1c2083373 ("clk: at91: rework main clk implementation") > Fixes: 1bdf02326b71e ("clk: at91: make use of syscon/regmap internally") Is this really a fix? What is the observed issue? > Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com> > --- > drivers/clk/at91/clk-main.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c > index 37c22667e831..46b4d2131989 100644 > --- a/drivers/clk/at91/clk-main.c > +++ b/drivers/clk/at91/clk-main.c > @@ -74,13 +74,11 @@ static int clk_main_osc_prepare(struct clk_hw *hw) > regmap_read(regmap, AT91_CKGR_MOR, &tmp); > tmp &= ~MOR_KEY_MASK; > > - if (tmp & AT91_PMC_OSCBYPASS) > + if (tmp & (AT91_PMC_OSCBYPASS | AT91_PMC_MOSCEN)) > return 0; While this seems like a good optimization, it is also not correct. Having AT91_PMC_MOSCEN set doesn't mean that the clock is ready, you need to at least check MOSCS once. > > - if (!(tmp & AT91_PMC_MOSCEN)) { > - tmp |= AT91_PMC_MOSCEN | AT91_PMC_KEY; > - regmap_write(regmap, AT91_CKGR_MOR, tmp); > - } > + tmp |= AT91_PMC_MOSCEN | AT91_PMC_KEY; > + regmap_write(regmap, AT91_CKGR_MOR, tmp); > > while (!clk_main_osc_ready(regmap)) > cpu_relax(); > @@ -186,10 +184,12 @@ static int clk_main_rc_osc_prepare(struct clk_hw *hw) > > regmap_read(regmap, AT91_CKGR_MOR, &mor); > > - if (!(mor & AT91_PMC_MOSCRCEN)) > - regmap_update_bits(regmap, AT91_CKGR_MOR, > - MOR_KEY_MASK | AT91_PMC_MOSCRCEN, > - AT91_PMC_MOSCRCEN | AT91_PMC_KEY); > + if (mor & AT91_PMC_MOSCRCEN) > + return 0; > + > + regmap_update_bits(regmap, AT91_CKGR_MOR, > + MOR_KEY_MASK | AT91_PMC_MOSCRCEN, > + AT91_PMC_MOSCRCEN | AT91_PMC_KEY); > > while (!clk_main_rc_osc_ready(regmap)) > cpu_relax(); > -- > 2.7.4 > -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-06-26 21:04 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-25 10:09 [PATCH 1/2] clk: at91: remove the checking of parent_name Claudiu Beznea 2020-06-25 10:09 ` Claudiu Beznea 2020-06-25 10:09 ` [PATCH 2/2] clk: at91: main: do not continue if oscillators already prepared Claudiu Beznea 2020-06-25 10:09 ` Claudiu Beznea 2020-06-26 21:03 ` Alexandre Belloni [this message] 2020-06-26 21:03 ` Alexandre Belloni 2020-07-01 9:47 ` Claudiu.Beznea 2020-07-01 9:47 ` Claudiu.Beznea 2020-06-26 20:58 ` [PATCH 1/2] clk: at91: remove the checking of parent_name Alexandre Belloni 2020-06-26 20:58 ` Alexandre Belloni
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