2021-03-05 13:31:39

by Wolfram Sang

[permalink] [raw]
Subject: [PATCH] clocksource: sh_cmt: use CMTOUT_IE only when supported

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

Reported-by: Phong Hoang <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
---

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


2021-03-08 08:48:28

by Geert Uytterhoeven

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

Hi Wolfram, Phong-san,

On Fri, Mar 5, 2021 at 2:30 PM Wolfram Sang
<[email protected]> 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 <[email protected]>
> Signed-off-by: Wolfram Sang <[email protected]>

Thanks for your patch!

As R-Car Gen2/3 indeed don't have this bit:
Reviewed-by: Geert Uytterhoeven <[email protected]>

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 -- [email protected]

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

2021-03-08 12:08:24

by Niklas Söderlund

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

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 <[email protected]>
> Signed-off-by: Wolfram Sang <[email protected]>

Reviewed-by: Niklas S?derlund <[email protected]>

> ---
>
> 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 S?derlund

2021-03-09 09:37:06

by Wolfram Sang

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


> 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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