Re: [RESEND PATCH v4] clk: stm32f4: fix post divisor setup for I2S/SAI PLLs

[Dario Binacchi <dariobin@libero.it>]

Hi Dillon and Stephen,

> Il 01/08/2021 16:56 Dillon Hua <dillonhua@gmail.com> ha scritto:
> 
>  
> Hi Dario
> 
> On Thu, Jul 29, 2021 at 6:03 PM Dario Binacchi <dariobin@libero.it> wrote:
> >
> > Hi Dillon,
> >
> > > Il 28/07/2021 12:03 Dillon Hua <dillonhua@gmail.com> ha scritto:
> > >
> > >
> > > Hi Dario,
> > >
> > > I have a similar patch [1] submitted last year.
> > > Unfortunately, it did not get accepted by the maintainer.
> > >
> > > Just a reminder here for you, should remove
> > >
> > > { STM32F4_RCC_APB2ENR, 26, "ltdc", "apb2_div" },
> >
> > Thank you for your suggestion.
> > While testing the patch on the stm32f469-disco board I didn't
> > notice the white screen issue. I'll try to run the tests again.
> > I will let you know.
> 
> Thanks, be sure clk_ignore_unused is not set from the kernel cmdline
> at your test.

This is the kernel command line of my tests:
console=ttySTM0,115200 root=/dev/mmcblk0p2 rw rootfstype=ext2 rootwait earlyprintk consoleblank=0 ignore_loglevel

In previous emails I forgot to mention that the patch was in turn applied to a buildroot patch [1] and
acked by Christophe Priouzeau of ST microelectronics. However, I rerun the tests and did not notice
anything strange.

I then enabled CONFIG_VT, CONFIG_FRAMEBUFFER_CONSOLE and CONFIG_LOGO, and indedd the command
'echo Dario >/dev/tty0' prints my name on the display only by removing
{STM32F4_RCC_APB2ENR, 26, "ltdc", "apb2_div"}.

As said in a previous email to Stephen, the patch I submitted fixes commit 517633ef630e
("clk: stm32f4: Add post divisor for I2S & SAI PLLs"), so IMHO it should not be dropped from the tree.
What Dillon suggested should instead be fixed by another patch.

Waiting for your opinion,
Thanks and regards,
Dario

[1] https://patchwork.ozlabs.org/project/buildroot/patch/20210716164243.17988-1-dariobin@libero.it/


> 
> Best Regards
> Dillon
> 
> >
> > Thanks and regards,
> > Dario
> >
> > >
> > > from stm32{f429, f469, f746, f769}_gates[]; or else
> > > run into white screen after the kernel enters the console.
> > >
> > > This patch was verified by Patrice Chotard, you can
> > > find  the history from [2].
> > >
> > > Hope you can help to submit a patch to include [2], thanks.
> > >
> > > [1]
> > > https://lore.kernel.org/linux-arm-kernel/1590564453-24499-7-git-send-email-dillon.minfei@gmail.com/
> > > https://lore.kernel.org/linux-arm-kernel/1590564453-24499-6-git-send-email-dillon.minfei@gmail.com/
> > >
> > > resend this year:
> > > https://lore.kernel.org/lkml/1590378348-8115-6-git-send-email-dillon.minfei@gmail.com/
> > >
> > > [2]
> > > https://lore.kernel.org/lkml/6915fa2a-e211-476f-8317-6825e280c322@foss.st.com/
> > >
> > > Thanks
> > > Best Regards
> > >
> > > Dillon
> > >
> > > On Mon, Jul 26, 2021 at 12:08 AM Dario Binacchi <dariobin@libero.it> wrote:
> > > >
> > > > Enabling the framebuffer leads to a system hang. Running, as a debug
> > > > hack, the store_pan() function in drivers/video/fbdev/core/fbsysfs.c
> > > > without taking the console_lock, allows to see the crash backtrace on
> > > > the serial line.
> > > >
> > > > ~ # echo 0 0 > /sys/class/graphics/fb0/pan
> > > >
> > > > [    9.719414] Unhandled exception: IPSR = 00000005 LR = fffffff1
> > > > [    9.726937] CPU: 0 PID: 49 Comm: sh Not tainted 5.13.0-rc5 #9
> > > > [    9.733008] Hardware name: STM32 (Device Tree Support)
> > > > [    9.738296] PC is at clk_gate_is_enabled+0x0/0x28
> > > > [    9.743426] LR is at stm32f4_pll_div_set_rate+0xf/0x38
> > > > [    9.748857] pc : [<0011e4be>]    lr : [<0011f9e3>]    psr: 0100000b
> > > > [    9.755373] sp : 00bc7be0  ip : 00000000  fp : 001f3ac4
> > > > [    9.760812] r10: 002610d0  r9 : 01efe920  r8 : 00540560
> > > > [    9.766269] r7 : 02e7ddb0  r6 : 0173eed8  r5 : 00000000  r4 : 004027c0
> > > > [    9.773081] r3 : 0011e4bf  r2 : 02e7ddb0  r1 : 0173eed8  r0 : 1d3267b8
> > > > [    9.779911] xPSR: 0100000b
> > > > [    9.782719] CPU: 0 PID: 49 Comm: sh Not tainted 5.13.0-rc5 #9
> > > > [    9.788791] Hardware name: STM32 (Device Tree Support)
> > > > [    9.794120] [<0000afa1>] (unwind_backtrace) from [<0000a33f>] (show_stack+0xb/0xc)
> > > > [    9.802421] [<0000a33f>] (show_stack) from [<0000a8df>] (__invalid_entry+0x4b/0x4c)
> > > >
> > > > The `pll_num' field in the post_div_data configuration contained a wrong
> > > > value which also referenced an uninitialized hardware clock when
> > > > clk_register_pll_div() was called.
> > > >
> > > > Fixes: 517633ef630e ("clk: stm32f4: Add post divisor for I2S & SAI PLLs")
> > > > Signed-off-by: Dario Binacchi <dariobin@libero.it>
> > > > Reviewed-by: Gabriel Fernandez <gabriel.fernandez@st.com>
> > > >
> > > > ---
> > > > I added Gabriel Fernandez's 'Reviewed-by' tag as requested by himself
> > > > 15 days ago at https://lore.kernel.org/patchwork/patch/1450964/.
> > > >
> > > > Changes in v4:
> > > > - Really add Gabriel Fernandez 'Reviewed-by' tag. In version 3 I forgot
> > > >   to add the tag.
> > > >
> > > > Changes in v3:
> > > > - Add Gabriel Fernandez 'Reviewed-by' tag.
> > > >
> > > > Changes in v2:
> > > > - Change  'u8 pll_num' from 'stm32f4_pll_post_div_data' structure into
> > > >   'int pll_idx'.
> > > >
> > > >  drivers/clk/clk-stm32f4.c | 10 +++++-----
> > > >  1 file changed, 5 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c
> > > > index 18117ce5ff85..5c75e3d906c2 100644
> > > > --- a/drivers/clk/clk-stm32f4.c
> > > > +++ b/drivers/clk/clk-stm32f4.c
> > > > @@ -526,7 +526,7 @@ struct stm32f4_pll {
> > > >
> > > >  struct stm32f4_pll_post_div_data {
> > > >         int idx;
> > > > -       u8 pll_num;
> > > > +       int pll_idx;
> > > >         const char *name;
> > > >         const char *parent;
> > > >         u8 flag;
> > > > @@ -557,13 +557,13 @@ 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 },
> > > >  };
> > > >
> > > > @@ -1774,7 +1774,7 @@ static void __init stm32f4_rcc_init(struct device_node *np)
> > > >                                 post_div->width,
> > > >                                 post_div->flag_div,
> > > >                                 post_div->div_table,
> > > > -                               clks[post_div->pll_num],
> > > > +                               clks[post_div->pll_idx],
> > > >                                 &stm32f4_clk_lock);
> > > >
> > > >                 if (post_div->idx != NO_IDX)
> > > > --
> > > > 2.17.1
> > > >