On 07/11/2022 08:22, Nancy.Lin wrote:
> Simplify code for update mmsys reg.
>
> Signed-off-by: Nancy.Lin <[email protected]>
> Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
> Reviewed-by: CK Hu <[email protected]>
> Tested-by: AngeloGioacchino Del Regno <[email protected]>
> Tested-by: Bo-Chen Chen <[email protected]>
> Reviewed-by: Nícolas F. R. A. Prado <[email protected]>
> ---
> drivers/soc/mediatek/mtk-mmsys.c | 45 ++++++++++++--------------------
> 1 file changed, 16 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/soc/mediatek/mtk-mmsys.c b/drivers/soc/mediatek/mtk-mmsys.c
> index 9a327eb5d9d7..73c8bd27e6ae 100644
> --- a/drivers/soc/mediatek/mtk-mmsys.c
> +++ b/drivers/soc/mediatek/mtk-mmsys.c
> @@ -99,22 +99,27 @@ struct mtk_mmsys {
> struct reset_controller_dev rcdev;
> };
>
> +static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
> +{
> + u32 tmp;
> +
> + tmp = readl_relaxed(mmsys->regs + offset);
> + tmp = (tmp & ~mask) | (val & mask);
I'm not sure about the change in the implementation of mtk_mmsys_update_bits().
Nicolas tried to explain it to me on IRC but I wasn't totally convincing. As we
have to go for at least another round of this patches, I'd like to get a clear
understanding while it is needed that val bits are set to 1 in the mask.
Regards,
Matthias
> + writel_relaxed(tmp, mmsys->regs + offset);
> +}
> +
> void mtk_mmsys_ddp_connect(struct device *dev,
> enum mtk_ddp_comp_id cur,
> enum mtk_ddp_comp_id next)
> {
> struct mtk_mmsys *mmsys = dev_get_drvdata(dev);
> const struct mtk_mmsys_routes *routes = mmsys->data->routes;
> - u32 reg;
> int i;
>
> for (i = 0; i < mmsys->data->num_routes; i++)
> - if (cur == routes[i].from_comp && next == routes[i].to_comp) {
> - reg = readl_relaxed(mmsys->regs + routes[i].addr);
> - reg &= ~routes[i].mask;
> - reg |= routes[i].val;
> - writel_relaxed(reg, mmsys->regs + routes[i].addr);
> - }
> + if (cur == routes[i].from_comp && next == routes[i].to_comp)
> + mtk_mmsys_update_bits(mmsys, routes[i].addr, routes[i].mask,
> + routes[i].val);
> }
> EXPORT_SYMBOL_GPL(mtk_mmsys_ddp_connect);
>
> @@ -124,27 +129,14 @@ void mtk_mmsys_ddp_disconnect(struct device *dev,
> {
> struct mtk_mmsys *mmsys = dev_get_drvdata(dev);
> const struct mtk_mmsys_routes *routes = mmsys->data->routes;
> - u32 reg;
> int i;
>
> for (i = 0; i < mmsys->data->num_routes; i++)
> - if (cur == routes[i].from_comp && next == routes[i].to_comp) {
> - reg = readl_relaxed(mmsys->regs + routes[i].addr);
> - reg &= ~routes[i].mask;
> - writel_relaxed(reg, mmsys->regs + routes[i].addr);
> - }
> + if (cur == routes[i].from_comp && next == routes[i].to_comp)
> + mtk_mmsys_update_bits(mmsys, routes[i].addr, routes[i].mask, 0);
> }
> EXPORT_SYMBOL_GPL(mtk_mmsys_ddp_disconnect);
>
> -static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
> -{
> - u32 tmp;
> -
> - tmp = readl_relaxed(mmsys->regs + offset);
> - tmp = (tmp & ~mask) | val;
> - writel_relaxed(tmp, mmsys->regs + offset);
> -}
> -
> void mtk_mmsys_ddp_dpi_fmt_config(struct device *dev, u32 val)
> {
> if (val)
> @@ -161,18 +153,13 @@ static int mtk_mmsys_reset_update(struct reset_controller_dev *rcdev, unsigned l
> {
> struct mtk_mmsys *mmsys = container_of(rcdev, struct mtk_mmsys, rcdev);
> unsigned long flags;
> - u32 reg;
>
> spin_lock_irqsave(&mmsys->lock, flags);
>
> - reg = readl_relaxed(mmsys->regs + mmsys->data->sw0_rst_offset);
> -
> if (assert)
> - reg &= ~BIT(id);
> + mtk_mmsys_update_bits(mmsys, mmsys->data->sw0_rst_offset, BIT(id), 0);
> else
> - reg |= BIT(id);
> -
> - writel_relaxed(reg, mmsys->regs + mmsys->data->sw0_rst_offset);
> + mtk_mmsys_update_bits(mmsys, mmsys->data->sw0_rst_offset, BIT(id), BIT(id));
>
> spin_unlock_irqrestore(&mmsys->lock, flags);
>
On Tue, Nov 08, 2022 at 06:37:19PM +0100, Matthias Brugger wrote:
>
>
> On 07/11/2022 08:22, Nancy.Lin wrote:
> > Simplify code for update mmsys reg.
> >
> > Signed-off-by: Nancy.Lin <[email protected]>
> > Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
> > Reviewed-by: CK Hu <[email protected]>
> > Tested-by: AngeloGioacchino Del Regno <[email protected]>
> > Tested-by: Bo-Chen Chen <[email protected]>
> > Reviewed-by: N?colas F. R. A. Prado <[email protected]>
> > ---
> > drivers/soc/mediatek/mtk-mmsys.c | 45 ++++++++++++--------------------
> > 1 file changed, 16 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/soc/mediatek/mtk-mmsys.c b/drivers/soc/mediatek/mtk-mmsys.c
> > index 9a327eb5d9d7..73c8bd27e6ae 100644
> > --- a/drivers/soc/mediatek/mtk-mmsys.c
> > +++ b/drivers/soc/mediatek/mtk-mmsys.c
> > @@ -99,22 +99,27 @@ struct mtk_mmsys {
> > struct reset_controller_dev rcdev;
> > };
> > +static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
> > +{
> > + u32 tmp;
> > +
> > + tmp = readl_relaxed(mmsys->regs + offset);
> > + tmp = (tmp & ~mask) | (val & mask);
>
> I'm not sure about the change in the implementation of
> mtk_mmsys_update_bits(). Nicolas tried to explain it to me on IRC but I
> wasn't totally convincing. As we have to go for at least another round of
> this patches, I'd like to get a clear understanding while it is needed that
> val bits are set to 1 in the mask.
The point here was to make sure that mtk_mmsys_update_bits() didn't allow
setting bits outside of the mask, since that's never what you want: the entire
point of having a mask is to specify the bits that should be updated (and the
ones that should be kept unchanged). So for example if you had
mask = 0x0ff0
val = 0x00ff
the previous implementation would happily overwrite the 4 least significant bits
on the destination register, despite them not being present in the mask, which
is wrong.
This wrong behavior could easily lead to hard to trace bugs as soon as a badly
formatted/wrong val is passed and an unrelated bit updated due to the mask being
ignored.
For reference, _regmap_update_bits() does the same masking of the value [1].
That said, given that this function already existed and was just being moved,
it would've been cleaner to make this change in a separate commit.
[1] https://elixir.bootlin.com/linux/latest/source/drivers/base/regmap/regmap.c#L3122
Thanks,
N?colas
>
> Regards,
> Matthias
>
> > + writel_relaxed(tmp, mmsys->regs + offset);
> > +}
[..]
> > -static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
> > -{
> > - u32 tmp;
> > -
> > - tmp = readl_relaxed(mmsys->regs + offset);
> > - tmp = (tmp & ~mask) | val;
> > - writel_relaxed(tmp, mmsys->regs + offset);
> > -}
> > -
[..]
On 08/11/2022 20:43, Nícolas F. R. A. Prado wrote:
> On Tue, Nov 08, 2022 at 06:37:19PM +0100, Matthias Brugger wrote:
>>
>>
>> On 07/11/2022 08:22, Nancy.Lin wrote:
>>> Simplify code for update mmsys reg.
>>>
>>> Signed-off-by: Nancy.Lin <[email protected]>
>>> Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
>>> Reviewed-by: CK Hu <[email protected]>
>>> Tested-by: AngeloGioacchino Del Regno <[email protected]>
>>> Tested-by: Bo-Chen Chen <[email protected]>
>>> Reviewed-by: Nícolas F. R. A. Prado <[email protected]>
>>> ---
>>> drivers/soc/mediatek/mtk-mmsys.c | 45 ++++++++++++--------------------
>>> 1 file changed, 16 insertions(+), 29 deletions(-)
>>>
>>> diff --git a/drivers/soc/mediatek/mtk-mmsys.c b/drivers/soc/mediatek/mtk-mmsys.c
>>> index 9a327eb5d9d7..73c8bd27e6ae 100644
>>> --- a/drivers/soc/mediatek/mtk-mmsys.c
>>> +++ b/drivers/soc/mediatek/mtk-mmsys.c
>>> @@ -99,22 +99,27 @@ struct mtk_mmsys {
>>> struct reset_controller_dev rcdev;
>>> };
>>> +static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
>>> +{
>>> + u32 tmp;
>>> +
>>> + tmp = readl_relaxed(mmsys->regs + offset);
>>> + tmp = (tmp & ~mask) | (val & mask);
>>
>> I'm not sure about the change in the implementation of
>> mtk_mmsys_update_bits(). Nicolas tried to explain it to me on IRC but I
>> wasn't totally convincing. As we have to go for at least another round of
>> this patches, I'd like to get a clear understanding while it is needed that
>> val bits are set to 1 in the mask.
>
> The point here was to make sure that mtk_mmsys_update_bits() didn't allow
> setting bits outside of the mask, since that's never what you want: the entire
> point of having a mask is to specify the bits that should be updated (and the
> ones that should be kept unchanged). So for example if you had
>
> mask = 0x0ff0
> val = 0x00ff
>
> the previous implementation would happily overwrite the 4 least significant bits
> on the destination register, despite them not being present in the mask, which
> is wrong.
>
> This wrong behavior could easily lead to hard to trace bugs as soon as a badly
> formatted/wrong val is passed and an unrelated bit updated due to the mask being
> ignored.
>
> For reference, _regmap_update_bits() does the same masking of the value [1].
>
> That said, given that this function already existed and was just being moved,
> it would've been cleaner to make this change in a separate commit.
>
Would have been better, but we can leave it as it.
Regards,
Matthias
> [1] https://elixir.bootlin.com/linux/latest/source/drivers/base/regmap/regmap.c#L3122
>
> Thanks,
> Nícolas
>
>>
>> Regards,
>> Matthias
>>
>>> + writel_relaxed(tmp, mmsys->regs + offset);
>>> +}
> [..]
>>> -static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
>>> -{
>>> - u32 tmp;
>>> -
>>> - tmp = readl_relaxed(mmsys->regs + offset);
>>> - tmp = (tmp & ~mask) | val;
>>> - writel_relaxed(tmp, mmsys->regs + offset);
>>> -}
>>> -
> [..]
Dear Matthias,
Thanks for the review.
On Thu, 2022-11-10 at 14:12 +0100, Matthias Brugger wrote:
>
> On 08/11/2022 20:43, Nícolas F. R. A. Prado wrote:
> > On Tue, Nov 08, 2022 at 06:37:19PM +0100, Matthias Brugger wrote:
> > >
> > >
> > > On 07/11/2022 08:22, Nancy.Lin wrote:
> > > > Simplify code for update mmsys reg.
> > > >
> > > > Signed-off-by: Nancy.Lin <[email protected]>
> > > > Reviewed-by: AngeloGioacchino Del Regno <
> > > > [email protected]>
> > > > Reviewed-by: CK Hu <[email protected]>
> > > > Tested-by: AngeloGioacchino Del Regno <
> > > > [email protected]>
> > > > Tested-by: Bo-Chen Chen <[email protected]>
> > > > Reviewed-by: Nícolas F. R. A. Prado <[email protected]>
> > > > ---
> > > > drivers/soc/mediatek/mtk-mmsys.c | 45 ++++++++++++--------
> > > > ------------
> > > > 1 file changed, 16 insertions(+), 29 deletions(-)
> > > >
> > > > diff --git a/drivers/soc/mediatek/mtk-mmsys.c
> > > > b/drivers/soc/mediatek/mtk-mmsys.c
> > > > index 9a327eb5d9d7..73c8bd27e6ae 100644
> > > > --- a/drivers/soc/mediatek/mtk-mmsys.c
> > > > +++ b/drivers/soc/mediatek/mtk-mmsys.c
> > > > @@ -99,22 +99,27 @@ struct mtk_mmsys {
> > > > struct reset_controller_dev rcdev;
> > > > };
> > > > +static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32
> > > > offset, u32 mask, u32 val)
> > > > +{
> > > > + u32 tmp;
> > > > +
> > > > + tmp = readl_relaxed(mmsys->regs + offset);
> > > > + tmp = (tmp & ~mask) | (val & mask);
> > >
> > > I'm not sure about the change in the implementation of
> > > mtk_mmsys_update_bits(). Nicolas tried to explain it to me on IRC
> > > but I
> > > wasn't totally convincing. As we have to go for at least another
> > > round of
> > > this patches, I'd like to get a clear understanding while it is
> > > needed that
> > > val bits are set to 1 in the mask.
> >
> > The point here was to make sure that mtk_mmsys_update_bits() didn't
> > allow
> > setting bits outside of the mask, since that's never what you want:
> > the entire
> > point of having a mask is to specify the bits that should be
> > updated (and the
> > ones that should be kept unchanged). So for example if you had
> >
> > mask = 0x0ff0
> > val = 0x00ff
> >
> > the previous implementation would happily overwrite the 4 least
> > significant bits
> > on the destination register, despite them not being present in the
> > mask, which
> > is wrong.
> >
> > This wrong behavior could easily lead to hard to trace bugs as soon
> > as a badly
> > formatted/wrong val is passed and an unrelated bit updated due to
> > the mask being
> > ignored.
> >
> > For reference, _regmap_update_bits() does the same masking of the
> > value [1].
> >
> > That said, given that this function already existed and was just
> > being moved,
> > it would've been cleaner to make this change in a separate commit.
> >
>
> Would have been better, but we can leave it as it.
>
> Regards,
> Matthias
>
Do you mean to keep original one (1), or keep this (2) ?
1. tmp = (tmp & ~mask) | val;
2. tmp = (tmp & ~mask) | (val & mask);
Regards,
Nancy
> > [1]
> > https://urldefense.com/v3/__https://elixir.bootlin.com/linux/latest/source/drivers/base/regmap/regmap.c*L3122__;Iw!!CTRNKA9wMg0ARbw!xSv5xbY6cv-Mg-1xDGOf3oVZ93uyrcv4tt87DKlx5emjmwufjf2DjION7GiNAaJB$
> >
> >
> > Thanks,
> > Nícolas
> >
> > >
> > > Regards,
> > > Matthias
> > >
> > > > + writel_relaxed(tmp, mmsys->regs + offset);
> > > > +}
> >
> > [..]
> > > > -static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32
> > > > offset, u32 mask, u32 val)
> > > > -{
> > > > - u32 tmp;
> > > > -
> > > > - tmp = readl_relaxed(mmsys->regs + offset);
> > > > - tmp = (tmp & ~mask) | val;
> > > > - writel_relaxed(tmp, mmsys->regs + offset);
> > > > -}
> > > > -
> >
> > [..]
>
>