[PATCH] clocksource: sh_cmt: use CMTOUT_IE only when supported

[PATCH] clocksource: sh_cmt: use CMTOUT_IE only when supported

[Wolfram Sang]

CMTOUT_IE is only supported for older SoCs. Newer SoCs shall not set
this bit. So, add a version check.

Reported-by: Phong Hoang <phong.hoang.wz@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Confirmed with datasheets and could successfully repeat Niklas' CMT
tests on an R-Car M3N based Salvator-XS.

 drivers/clocksource/sh_cmt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
index c98f8851fd68..3b53c6cb1da9 100644
--- a/drivers/clocksource/sh_cmt.c
+++ b/drivers/clocksource/sh_cmt.c
@@ -143,6 +143,7 @@ struct sh_cmt_device {
 #define SH_CMT32_CMCSR_SSIE		(1 << 10)
 #define SH_CMT32_CMCSR_CMS		(1 << 9)
 #define SH_CMT32_CMCSR_CMM		(1 << 8)
+/* CMTOUT_IE only for SH_CMT_32BIT and SH_CMT_48BIT */
 #define SH_CMT32_CMCSR_CMTOUT_IE	(1 << 7)
 #define SH_CMT32_CMCSR_CMR_NONE		(0 << 4)
 #define SH_CMT32_CMCSR_CMR_DMA		(1 << 4)
@@ -339,8 +340,9 @@ static int sh_cmt_enable(struct sh_cmt_channel *ch)
 		sh_cmt_write_cmcsr(ch, SH_CMT16_CMCSR_CMIE |
 				   SH_CMT16_CMCSR_CKS512);
 	} else {
-		sh_cmt_write_cmcsr(ch, SH_CMT32_CMCSR_CMM |
-				   SH_CMT32_CMCSR_CMTOUT_IE |
+		u32 cmtout = ch->cmt->info->model <= SH_CMT_48BIT ?
+			      SH_CMT32_CMCSR_CMTOUT_IE : 0;
+		sh_cmt_write_cmcsr(ch, cmtout | SH_CMT32_CMCSR_CMM |
 				   SH_CMT32_CMCSR_CMR_IRQ |
 				   SH_CMT32_CMCSR_CKS_RCLK8);
 	}
-- 
2.29.2

Re: [PATCH] clocksource: sh_cmt: use CMTOUT_IE only when supported

[Geert Uytterhoeven]

Hi Wolfram, Phong-san,

On Fri, Mar 5, 2021 at 2:30 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> CMTOUT_IE is only supported for older SoCs. Newer SoCs shall not set
> this bit. So, add a version check.
>
> Reported-by: Phong Hoang <phong.hoang.wz@renesas.com>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Thanks for your patch!

As R-Car Gen2/3 indeed don't have this bit:
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

But given my comments below, I think it would make sense to change the
one-line summary to e.g. "clocksource: sh_cmt: R-Car Gen2/Gen3 do not
have CMTOUT_IE".

> --- a/drivers/clocksource/sh_cmt.c
> +++ b/drivers/clocksource/sh_cmt.c
> @@ -143,6 +143,7 @@ struct sh_cmt_device {
>  #define SH_CMT32_CMCSR_SSIE            (1 << 10)
>  #define SH_CMT32_CMCSR_CMS             (1 << 9)
>  #define SH_CMT32_CMCSR_CMM             (1 << 8)
> +/* CMTOUT_IE only for SH_CMT_32BIT and SH_CMT_48BIT */
>  #define SH_CMT32_CMCSR_CMTOUT_IE       (1 << 7)
>  #define SH_CMT32_CMCSR_CMR_NONE                (0 << 4)
>  #define SH_CMT32_CMCSR_CMR_DMA         (1 << 4)
> @@ -339,8 +340,9 @@ static int sh_cmt_enable(struct sh_cmt_channel *ch)
>                 sh_cmt_write_cmcsr(ch, SH_CMT16_CMCSR_CMIE |
>                                    SH_CMT16_CMCSR_CKS512);
>         } else {
> -               sh_cmt_write_cmcsr(ch, SH_CMT32_CMCSR_CMM |
> -                                  SH_CMT32_CMCSR_CMTOUT_IE |
> +               u32 cmtout = ch->cmt->info->model <= SH_CMT_48BIT ?
> +                             SH_CMT32_CMCSR_CMTOUT_IE : 0;
> +               sh_cmt_write_cmcsr(ch, cmtout | SH_CMT32_CMCSR_CMM |
>                                    SH_CMT32_CMCSR_CMR_IRQ |
>                                    SH_CMT32_CMCSR_CKS_RCLK8);
>         }

Note that this bit is still set for all "32-bit" and all other "48-bit"
variants:

SH_CMT_32BIT:
sh7720: CMTOUT_IE supported
sh7343/7366: no docs
sh7722/sh7723: limited docs, but "Supports canceling of the standby
state in U-standby mode."
sh7724: CMTOUT_IE supported

SH_CMT_48BIT:
sh73a0/r8a7740: CMTOUT_IE supported on channels 1/2/3, not on 0/4/5

So even not all older models support this bit.
Probably this bit should only be set when the timer is configured as a
wake-up source.  But that is out-of-scope for this patch.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] clocksource: sh_cmt: use CMTOUT_IE only when supported

[Niklas Söderlund]

Hi Wolfram,

Thanks for your patch.

On 2021-03-05 14:28:59 +0100, Wolfram Sang wrote:
> CMTOUT_IE is only supported for older SoCs. Newer SoCs shall not set
> this bit. So, add a version check.
> 
> Reported-by: Phong Hoang <phong.hoang.wz@renesas.com>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
> 
> Confirmed with datasheets and could successfully repeat Niklas' CMT
> tests on an R-Car M3N based Salvator-XS.
> 
>  drivers/clocksource/sh_cmt.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
> index c98f8851fd68..3b53c6cb1da9 100644
> --- a/drivers/clocksource/sh_cmt.c
> +++ b/drivers/clocksource/sh_cmt.c
> @@ -143,6 +143,7 @@ struct sh_cmt_device {
>  #define SH_CMT32_CMCSR_SSIE		(1 << 10)
>  #define SH_CMT32_CMCSR_CMS		(1 << 9)
>  #define SH_CMT32_CMCSR_CMM		(1 << 8)
> +/* CMTOUT_IE only for SH_CMT_32BIT and SH_CMT_48BIT */
>  #define SH_CMT32_CMCSR_CMTOUT_IE	(1 << 7)
>  #define SH_CMT32_CMCSR_CMR_NONE		(0 << 4)
>  #define SH_CMT32_CMCSR_CMR_DMA		(1 << 4)
> @@ -339,8 +340,9 @@ static int sh_cmt_enable(struct sh_cmt_channel *ch)
>  		sh_cmt_write_cmcsr(ch, SH_CMT16_CMCSR_CMIE |
>  				   SH_CMT16_CMCSR_CKS512);
>  	} else {
> -		sh_cmt_write_cmcsr(ch, SH_CMT32_CMCSR_CMM |
> -				   SH_CMT32_CMCSR_CMTOUT_IE |
> +		u32 cmtout = ch->cmt->info->model <= SH_CMT_48BIT ?
> +			      SH_CMT32_CMCSR_CMTOUT_IE : 0;
> +		sh_cmt_write_cmcsr(ch, cmtout | SH_CMT32_CMCSR_CMM |
>  				   SH_CMT32_CMCSR_CMR_IRQ |
>  				   SH_CMT32_CMCSR_CKS_RCLK8);
>  	}
> -- 
> 2.29.2
> 

-- 
Regards,
Niklas Söderlund

Re: [PATCH] clocksource: sh_cmt: use CMTOUT_IE only when supported

[Wolfram Sang]

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> But given my comments below, I think it would make sense to change the
> one-line summary to e.g. "clocksource: sh_cmt: R-Car Gen2/Gen3 do not
> have CMTOUT_IE".

Makes sense. I will resend.

> SH_CMT_48BIT:
> sh73a0/r8a7740: CMTOUT_IE supported on channels 1/2/3, not on 0/4/5

Oh, I didn't spot this, sorry!

> So even not all older models support this bit.
> Probably this bit should only be set when the timer is configured as a
> wake-up source.  But that is out-of-scope for this patch.

Ack.


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