Messages in this thread Patch in this message | | | From | Nicolas Boichat <> | Date | Thu, 23 Jul 2020 15:51:50 +0800 | Subject | Re: [PATCH 3/4] clk: mediatek: Add configurable enable control to mtk_pll_data |
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On Thu, Jul 23, 2020 at 10:57 AM Weiyi Lu <weiyi.lu@mediatek.com> wrote: > > On Wed, 2020-07-22 at 16:51 +0800, Nicolas Boichat wrote: > > On Wed, Jul 22, 2020 at 2:50 PM Weiyi Lu <weiyi.lu@mediatek.com> wrote: > > > > > > In all MediaTek PLL design, bit 0 of CON0 register is always > > > the enable bit. > > > However, there's a special case of usbpll on MT8192. > > > The enable bit of usbpll is moved to bit 2 of other register. > > > Add configurable en_reg and base_en_bit for enable control or > > > using the default if without setting in pll data. > > > > > > Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com> > > > --- > > > drivers/clk/mediatek/clk-mtk.h | 2 ++ > > > drivers/clk/mediatek/clk-pll.c | 26 ++++++++++++++++++++++---- > > > 2 files changed, 24 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h > > > index c3d6756..8bb0b3d 100644 > > > --- a/drivers/clk/mediatek/clk-mtk.h > > > +++ b/drivers/clk/mediatek/clk-mtk.h > > > @@ -233,6 +233,8 @@ struct mtk_pll_data { > > > uint32_t pcw_chg_reg; > > > const struct mtk_pll_div_table *div_table; > > > const char *parent_name; > > > + uint32_t en_reg; > > > + uint8_t base_en_bit; > > > }; > > > > > > void mtk_clk_register_plls(struct device_node *node, > > > diff --git a/drivers/clk/mediatek/clk-pll.c b/drivers/clk/mediatek/clk-pll.c > > > index f440f2cd..b8ccd42 100644 > > > --- a/drivers/clk/mediatek/clk-pll.c > > > +++ b/drivers/clk/mediatek/clk-pll.c > > > @@ -44,6 +44,7 @@ struct mtk_clk_pll { > > > void __iomem *tuner_en_addr; > > > void __iomem *pcw_addr; > > > void __iomem *pcw_chg_addr; > > > + void __iomem *en_addr; > > > const struct mtk_pll_data *data; > > > }; > > > > > > @@ -56,7 +57,10 @@ static int mtk_pll_is_prepared(struct clk_hw *hw) > > > { > > > struct mtk_clk_pll *pll = to_mtk_clk_pll(hw); > > > > > > - return (readl(pll->base_addr + REG_CON0) & CON0_BASE_EN) != 0; > > > + if (pll->en_addr) > > > + return (readl(pll->en_addr) & BIT(pll->data->base_en_bit)) != 0; > > > + else > > > + return (readl(pll->base_addr + REG_CON0) & CON0_BASE_EN) != 0; > > > } > > > > > > static unsigned long __mtk_pll_recalc_rate(struct mtk_clk_pll *pll, u32 fin, > > > @@ -251,6 +255,12 @@ static int mtk_pll_prepare(struct clk_hw *hw) > > > r |= pll->data->en_mask; > > > writel(r, pll->base_addr + REG_CON0); > > > > > > > This is not a new change, but I'm wondering if the asymmetry is > > intentional here, that is, prepare sets bit pll->data->en_mask of > > REG_CON0; unprepare clears CON0_BASE_EN of REG_CON0. > > > > With this patch, if pll->en_addr is set, you set both > > pll->data->en_mask _and_ pll->data->base_en_bit, and clear only > > pll->data->base_en_bit. > > > > Hi Nicolas, > > AFAIK, the asymmetry was intentional. > en_mask is actually a combination of divider enable mask and the pll > enable bit(CON0_BASE_EN). > Even without my patch, it still sets divider enable mask and en_bit, and > only clears en_bit. > You could see the pll_data in clk-mt8192.c of patch [4/4] > Take mainpll as an example, > the enable mask of mainpll is 0xff000001, where 0xff000000 is the > divider enable mask and 0x1 is the en_bit > > For usbpll in special case, usbpll doesn't have divider enable mask on > MT8192 so I give nothing(0x00000000) in the en_mask field. > However, the main reason why I don't skip setting the en_mask of MT8192 > usbpll is that I'd just like to reserve the divider enable mask for any > special plls with divider enable mask in near future.
Argh, I see, it's a bit of a can of worms, with many special cases...
So I played a bit with 3 examples.
Current situation looks like this:
8183 CLK_APMIXED_ARMPLL_LL en_mask = 0x00000001 en_reg = 0 base_en_bit = 0
prepare: REG_CON0 |= en_mask unprepare: REG_CON0 &= ~CON0_BASE_EN (BIT(1))
8192 CLK_APMIXED_UNIVPLL en_mask = 0xff000001 en_reg = 0x039c base_en_bit = 0
prepare: REG_CON0 |= en_mask en_reg |= base_en_bit unprepare: en_reg &= ~base_en_bit
8192 CLK_APMIXED_USBPLL en_mask = 0x00000000 en_reg = 0x03cc base_en_bit = 2
prepare: REG_CON0 |= en_mask (0) en_reg |= base_en_bit unprepare: en_reg &= ~base_en_bit
And I think the logic could still be simplified by _not_ putting CON0_BASE_EN in en_mask, and updating the CON0 in 2 steps: first all the bits that are not CON0_BASE_EN, then CON0_BASE_EN. Of course I assume that's it's fine to do so, but I have no idea.
register_pll() { if (!en_addr) { en_reg = REG_CON0 base_en_bit = CON0_BASE_EN } }
prepare() { REG_CON0 |= en_mask en_reg |= base_en_bit }
unprepare() { en_reg &= ~base_en_bit }
Then the new clock data:
8183 CLK_APMIXED_ARMPLL_LL en_mask = 0x00000000 (CON0_BASE_EN is implicit, but other bits could be set) en_reg = 0 base_en_bit = 0
prepare: { REG_CON0 |= en_mask (0x00000000, here, we can skip, but other bits could be set) en_reg |= base_en_bit (REG_CON0 |= CON0_BASE_EN) } unprepare: en_reg &= ~base_en_bit (REG_CON0 &= ~CON0_BASE_EN)
8192 CLK_APMIXED_UNIVPLL en_mask = 0xff000001 (Note the bit 1 is _not_ dropped here, as it needs to be set too) en_reg = 0x039c base_en_bit = 0 (same as above)
8192 CLK_APMIXED_USBPLL en_mask = 0x00000000 en_reg = 0x03cc base_en_bit = 2 (same as above)
Now, maybe this is also a bit overcomplicated. Maybe a simpler solution is just to add a comment in prepare that "r |= pll->data->en_mask;" is meant to include CON0_BASE_EN in most cases, and then the code could be ok as-is (just to make sure that the next person who looks at this code does not think there is a bug...).
> > > > + if (pll->en_addr) { > > > + r = readl(pll->en_addr); > > > + r |= BIT(pll->data->base_en_bit); > > > + writel(r, pll->en_addr); > > > + } > > > + > > > __mtk_pll_tuner_enable(pll); > > > > > > udelay(20); > > > @@ -277,9 +287,15 @@ static void mtk_pll_unprepare(struct clk_hw *hw) > > > > > > __mtk_pll_tuner_disable(pll); > > > > > > - r = readl(pll->base_addr + REG_CON0); > > > - r &= ~CON0_BASE_EN; > > > - writel(r, pll->base_addr + REG_CON0); > > > + if (pll->en_addr) { > > > + r = readl(pll->en_addr); > > > + r &= ~BIT(pll->data->base_en_bit); > > > + writel(r, pll->en_addr); > > > + } else { > > > + r = readl(pll->base_addr + REG_CON0); > > > + r &= ~CON0_BASE_EN; > > > + writel(r, pll->base_addr + REG_CON0); > > > + } > > > > > > r = readl(pll->pwr_addr) | CON0_ISO_EN; > > > writel(r, pll->pwr_addr); > > > @@ -321,6 +337,8 @@ static struct clk *mtk_clk_register_pll(const struct mtk_pll_data *data, > > > pll->tuner_addr = base + data->tuner_reg; > > > if (data->tuner_en_reg) > > > pll->tuner_en_addr = base + data->tuner_en_reg; > > > + if (data->en_reg) > > > + pll->en_addr = base + data->en_reg; > > > > If the answer to my question above holds (asymmetry is not > > intentional), this patch/the code could be simplified a lot if you > > also added a pll->en_bit member, and, here, did this: > > > > if (pll->en_reg) { > > pll->en_addr = base + data->en_reg; > > pll->end_bit = data->en_bit; > > } else { > > pll->en_addr = pll->base_addr + REG_CON0; > > pll->en_bit = CON0_BASE_EN; > > } > > > > > pll->hw.init = &init; > > > pll->data = data; > > > > > > -- > > > 1.8.1.1.dirty >
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