From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jerome Brunet Subject: Re: [1/5] clk: divider: read-only divider can propagate rate change Date: Wed, 17 Jan 2018 17:39:51 +0100 Message-ID: <1516207191.2608.122.camel@baylibre.com> References: <20180105170959.17266-2-jbrunet@baylibre.com> <999439aa-276a-575d-d6dc-6e9d1bdf5b15@lechnology.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <999439aa-276a-575d-d6dc-6e9d1bdf5b15@lechnology.com> Sender: linux-kernel-owner@vger.kernel.org To: David Lechner , Stephen Boyd , Michael Turquette , linux-clk@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, Vladimir Zapolskiy , Sylvain Lemieux , Andy Gross , David Brown List-Id: linux-arm-msm@vger.kernel.org On Thu, 2018-01-11 at 16:55 -0600, David Lechner wrote: > On 01/05/2018 11:09 AM, Jerome Brunet wrote: > > When a divider clock has CLK_DIVIDER_READ_ONLY set, it means that the > > register shall be left un-touched, but it does not mean the clock > > should stop rate propagation if CLK_SET_RATE_PARENT is set > > > > This is properly handled in qcom clk-regmap-divider but it was not in > > the generic divider > > > > Fixes: e6d5e7d90be9 ("clk-divider: Fix READ_ONLY when divider > 1") > > Signed-off-by: Jerome Brunet > > --- > > drivers/clk/clk-divider.c | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c > > index b49942b9fe50..a851d3e04c7f 100644 > > --- a/drivers/clk/clk-divider.c > > +++ b/drivers/clk/clk-divider.c > > @@ -348,6 +348,7 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, > > unsigned long *prate) > > { > > struct clk_divider *divider = to_clk_divider(hw); > > + struct clk_hw *hw_parent = clk_hw_get_parent(hw); > > Very minor suggestion: This could be moved inside the if block since it is only used there. Even if correct, this is something I have seen done in CCF. I tend to just follow the way to be honest. Stephen, do you have any preference ? > > > int bestdiv; > > > > /* if read only, just return current value */ > > @@ -356,6 +357,15 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, > > bestdiv &= div_mask(divider->width); > > bestdiv = _get_div(divider->table, bestdiv, divider->flags, > > divider->width); > > + > > + /* Even a read-only clock can propagate a rate change */ > > + if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) { > > + if (!hw_parent) > > + return -EINVAL; > > + > > + *prate = clk_hw_round_rate(hw_parent, rate * bestdiv); > > + } > > + > > return DIV_ROUND_UP_ULL((u64)*prate, bestdiv); > > } > > > > > > Tested-by: David Lechner From mboxrd@z Thu Jan 1 00:00:00 1970 From: jbrunet@baylibre.com (Jerome Brunet) Date: Wed, 17 Jan 2018 17:39:51 +0100 Subject: [1/5] clk: divider: read-only divider can propagate rate change In-Reply-To: <999439aa-276a-575d-d6dc-6e9d1bdf5b15@lechnology.com> References: <20180105170959.17266-2-jbrunet@baylibre.com> <999439aa-276a-575d-d6dc-6e9d1bdf5b15@lechnology.com> Message-ID: <1516207191.2608.122.camel@baylibre.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 2018-01-11 at 16:55 -0600, David Lechner wrote: > On 01/05/2018 11:09 AM, Jerome Brunet wrote: > > When a divider clock has CLK_DIVIDER_READ_ONLY set, it means that the > > register shall be left un-touched, but it does not mean the clock > > should stop rate propagation if CLK_SET_RATE_PARENT is set > > > > This is properly handled in qcom clk-regmap-divider but it was not in > > the generic divider > > > > Fixes: e6d5e7d90be9 ("clk-divider: Fix READ_ONLY when divider > 1") > > Signed-off-by: Jerome Brunet > > --- > > drivers/clk/clk-divider.c | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c > > index b49942b9fe50..a851d3e04c7f 100644 > > --- a/drivers/clk/clk-divider.c > > +++ b/drivers/clk/clk-divider.c > > @@ -348,6 +348,7 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, > > unsigned long *prate) > > { > > struct clk_divider *divider = to_clk_divider(hw); > > + struct clk_hw *hw_parent = clk_hw_get_parent(hw); > > Very minor suggestion: This could be moved inside the if block since it is only used there. Even if correct, this is something I have seen done in CCF. I tend to just follow the way to be honest. Stephen, do you have any preference ? > > > int bestdiv; > > > > /* if read only, just return current value */ > > @@ -356,6 +357,15 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, > > bestdiv &= div_mask(divider->width); > > bestdiv = _get_div(divider->table, bestdiv, divider->flags, > > divider->width); > > + > > + /* Even a read-only clock can propagate a rate change */ > > + if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) { > > + if (!hw_parent) > > + return -EINVAL; > > + > > + *prate = clk_hw_round_rate(hw_parent, rate * bestdiv); > > + } > > + > > return DIV_ROUND_UP_ULL((u64)*prate, bestdiv); > > } > > > > > > Tested-by: David Lechner