linux-kernel - Re: [PATCH 3/7] clk: stm32: Fix ltdc's clock turn off by clk_disable

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Date:   Thu, 17 Jun 2021 18:21:46 +0800
From:   Dillon Min <dillon.minfei@...il.com>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        mchehab+huawei@...nel.org, ezequiel@...labora.com,
        gnurou@...il.com, Pi-Hsun Shih <pihsun@...omium.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre TORGUE <alexandre.torgue@...s.st.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Patrice CHOTARD <patrice.chotard@...s.st.com>,
        hugues.fruchet@...s.st.com,
        linux-media <linux-media@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-stm32@...md-mailman.stormreply.com,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH 3/7] clk: stm32: Fix ltdc's clock turn off by
 clk_disable_unused() after kernel startup

Hi Hans,

On Thu, Jun 17, 2021 at 5:57 PM Hans Verkuil <hverkuil-cisco@...all.nl> wrote:
>
> On 20/05/2021 13:05, dillon.minfei@...il.com wrote:
> > From: Dillon Min <dillon.minfei@...il.com>
> >
> > stm32's clk driver register two ltdc gate clk to clk core by
> > clk_hw_register_gate() and clk_hw_register_composite()
> >
> > first: 'stm32f429_gates[]', clk name is 'ltdc', which no user to use.
> > second: 'stm32f429_aux_clk[]', clk name is 'lcd-tft', used by ltdc driver
> >
> > both of them point to the same offset of stm32's RCC register. after
> > kernel enter console, clk core turn off ltdc's clk as 'stm32f429_gates[]'
> > is no one to use. but, actually 'stm32f429_aux_clk[]' is in use.
> >
> > Fixes: daf2d117cbca ("clk: stm32f4: Add lcd-tft clock")
> > Signed-off-by: Dillon Min <dillon.minfei@...il.com>
> > Acked-by: Stephen Boyd <sboyd@...nel.org>
> > Link: https://lore.kernel.org/linux-arm-kernel/1590564453-24499-7-git-send-email-dillon.minfei@gmail.com/
>
> For my understanding: this patch is going/has already gone in via a different
> subsystem, right? And I should skip it when adding this driver to the media subsystem?

Yes, Just ignore this patch please.

It's only to make st's engineer easier to verify the dma2d driver,
since the board's lcd panel depends on this patch to work

stm32f469-disco board :
https://www.st.com/content/st_com/en/products/evaluation-tools/product-evaluation-tools/mcu-mpu-eval-tools/stm32-mcu-mpu-eval-tools/stm32-discovery-kits/32f469idiscovery.html

Thanks
Best Regards

Dillon

>
> Regards,
>
>         Hans
>
> > ---
> >
> > This patch was submitted in
> > https://lore.kernel.org/lkml/1620990152-19255-1-git-send-email-dillon.minfei@gmail.com/
> >
> >  drivers/clk/clk-stm32f4.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c
> > index 18117ce5ff85..b6ab8c3a7994 100644
> > --- a/drivers/clk/clk-stm32f4.c
> > +++ b/drivers/clk/clk-stm32f4.c
> > @@ -211,7 +211,6 @@ static const struct stm32f4_gate_data stm32f469_gates[] __initconst = {
> >       { STM32F4_RCC_APB2ENR, 20,      "spi5",         "apb2_div" },
> >       { STM32F4_RCC_APB2ENR, 21,      "spi6",         "apb2_div" },
> >       { STM32F4_RCC_APB2ENR, 22,      "sai1",         "apb2_div" },
> > -     { STM32F4_RCC_APB2ENR, 26,      "ltdc",         "apb2_div" },
> >  };
> >
> >  static const struct stm32f4_gate_data stm32f746_gates[] __initconst = {
> > @@ -557,13 +556,13 @@ static const struct clk_div_table post_divr_table[] = {
> >
> >  #define MAX_POST_DIV 3
> >  static const struct stm32f4_pll_post_div_data  post_div_data[MAX_POST_DIV] = {
> > -     { CLK_I2SQ_PDIV, PLL_I2S, "plli2s-q-div", "plli2s-q",
> > +     { CLK_I2SQ_PDIV, PLL_VCO_I2S, "plli2s-q-div", "plli2s-q",
> >               CLK_SET_RATE_PARENT, STM32F4_RCC_DCKCFGR, 0, 5, 0, NULL},
> >
> > -     { CLK_SAIQ_PDIV, PLL_SAI, "pllsai-q-div", "pllsai-q",
> > +     { CLK_SAIQ_PDIV, PLL_VCO_SAI, "pllsai-q-div", "pllsai-q",
> >               CLK_SET_RATE_PARENT, STM32F4_RCC_DCKCFGR, 8, 5, 0, NULL },
> >
> > -     { NO_IDX, PLL_SAI, "pllsai-r-div", "pllsai-r", CLK_SET_RATE_PARENT,
> > +     { NO_IDX, PLL_VCO_SAI, "pllsai-r-div", "pllsai-r", CLK_SET_RATE_PARENT,
> >               STM32F4_RCC_DCKCFGR, 16, 2, 0, post_divr_table },
> >  };
> >
> >
>