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From: "Chanho Park" <chanho61.park@samsung.com>
To: "'Linus Walleij'" <linus.walleij@linaro.org>
Cc: "'Krzysztof Kozlowski'" <krzysztof.kozlowski@linaro.org>,
	"'Andi Shyti'" <andi@etezian.org>,
	"'Mark Brown'" <broonie@kernel.org>,
	"'Rob Herring'" <robh+dt@kernel.org>,
	"'Krzysztof Kozlowski'" <krzysztof.kozlowski+dt@linaro.org>,
	"'Alim Akhtar'" <alim.akhtar@samsung.com>,
	<devicetree@vger.kernel.org>, <linux-spi@vger.kernel.org>,
	<linux-samsung-soc@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v3 2/4] spi: s3c64xx: support custom value of internal clock divider
Date: Fri, 1 Jul 2022 16:08:43 +0900	[thread overview]
Message-ID: <000001d88d19$662ccae0$328660a0$@samsung.com> (raw)
In-Reply-To: <CACRpkdagXnR0jjHNOVgGkh_ZntfzF0h4D_+DX85jNy7q=6DNEw@mail.gmail.com>

> > Modern exynos SoCs such as Exynos Auto v9 have different internal
> > clock divider, for example "4". To support this internal value, this
> > adds clk_div of the s3c64xx_spi_port_config and assign "2" as the
> > default value to existing s3c64xx_spi_port_config.
> >
> > Signed-off-by: Chanho Park <chanho61.park@samsung.com>
> 
> While this gives a way to set up the default clock divider (which is
> fair) I think
> you should probably go the extra mile and make this clock divider a proper
> clock abstraction, so the driver can respect the DT standard property spi-
> max-frequency from Documentation/devicetree/bindings/spi/spi-peripheral-
> props.yaml
> 
> This actually isn't very hard: look for example in the PL111 driver, a
> hardware block that contains a similar internal clock divider:
> drivers/gpu/drm/pl111/pl111_display.c
> check how we define a clock from pl111_clk_div_ops.
> in pl111_init_clock_divider().
> 
> Then the driver probe() just grabs that clock and sets the frequency.
> The algorithms should be pretty much copy/paste.

Thanks for the suggestion. I'll look into it.

Best Regards,
Chanho Park


WARNING: multiple messages have this Message-ID (diff)
From: "Chanho Park" <chanho61.park@samsung.com>
To: "'Linus Walleij'" <linus.walleij@linaro.org>
Cc: "'Krzysztof Kozlowski'" <krzysztof.kozlowski@linaro.org>,
	"'Andi Shyti'" <andi@etezian.org>,
	"'Mark Brown'" <broonie@kernel.org>,
	"'Rob Herring'" <robh+dt@kernel.org>,
	"'Krzysztof Kozlowski'" <krzysztof.kozlowski+dt@linaro.org>,
	"'Alim Akhtar'" <alim.akhtar@samsung.com>,
	<devicetree@vger.kernel.org>, <linux-spi@vger.kernel.org>,
	<linux-samsung-soc@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v3 2/4] spi: s3c64xx: support custom value of internal clock divider
Date: Fri, 1 Jul 2022 16:08:43 +0900	[thread overview]
Message-ID: <000001d88d19$662ccae0$328660a0$@samsung.com> (raw)
In-Reply-To: <CACRpkdagXnR0jjHNOVgGkh_ZntfzF0h4D_+DX85jNy7q=6DNEw@mail.gmail.com>

> > Modern exynos SoCs such as Exynos Auto v9 have different internal
> > clock divider, for example "4". To support this internal value, this
> > adds clk_div of the s3c64xx_spi_port_config and assign "2" as the
> > default value to existing s3c64xx_spi_port_config.
> >
> > Signed-off-by: Chanho Park <chanho61.park@samsung.com>
> 
> While this gives a way to set up the default clock divider (which is
> fair) I think
> you should probably go the extra mile and make this clock divider a proper
> clock abstraction, so the driver can respect the DT standard property spi-
> max-frequency from Documentation/devicetree/bindings/spi/spi-peripheral-
> props.yaml
> 
> This actually isn't very hard: look for example in the PL111 driver, a
> hardware block that contains a similar internal clock divider:
> drivers/gpu/drm/pl111/pl111_display.c
> check how we define a clock from pl111_clk_div_ops.
> in pl111_init_clock_divider().
> 
> Then the driver probe() just grabs that clock and sets the frequency.
> The algorithms should be pretty much copy/paste.

Thanks for the suggestion. I'll look into it.

Best Regards,
Chanho Park


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  reply	other threads:[~2022-07-01  7:08 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20220629102527epcas2p4ab04f91877e5f744c4a4e37827d19ce8@epcas2p4.samsung.com>
2022-06-29 10:23 ` [PATCH v3 0/4] spi support for Exynos Auto v9 SoC Chanho Park
2022-06-29 10:23   ` Chanho Park
     [not found]   ` <CGME20220629102527epcas2p21c9ba830afdf5ec5a8afde4707206186@epcas2p2.samsung.com>
2022-06-29 10:23     ` [PATCH v3 1/4] spi: s3c64xx: support loopback mode Chanho Park
2022-06-29 10:23       ` Chanho Park
     [not found]   ` <CGME20220629102527epcas2p42e99f44d529d215623bd0e12a082d1dd@epcas2p4.samsung.com>
2022-06-29 10:23     ` [PATCH v3 2/4] spi: s3c64xx: support custom value of internal clock divider Chanho Park
2022-06-29 10:23       ` Chanho Park
2022-06-29 10:52       ` Andi Shyti
2022-06-29 10:52         ` Andi Shyti
2022-06-29 11:13       ` Krzysztof Kozlowski
2022-06-29 11:13         ` Krzysztof Kozlowski
2022-06-29 11:36       ` Mark Brown
2022-06-29 11:36         ` Mark Brown
2022-06-30  9:07       ` Linus Walleij
2022-06-30  9:07         ` Linus Walleij
2022-06-30  9:16       ` Linus Walleij
2022-06-30  9:16         ` Linus Walleij
2022-07-01  7:08         ` Chanho Park [this message]
2022-07-01  7:08           ` Chanho Park
     [not found]   ` <CGME20220629102527epcas2p17d7347cf06341193ec91b5f892e69217@epcas2p1.samsung.com>
2022-06-29 10:23     ` [PATCH v3 3/4] dt-bindings: samsung,spi: define exynosautov9 compatible Chanho Park
2022-06-29 10:23       ` Chanho Park
     [not found]   ` <CGME20220629102527epcas2p19e967e3647084cbfad1bff0b9390b4ad@epcas2p1.samsung.com>
2022-06-29 10:23     ` [PATCH v3 4/4] spi: s3c64xx: add spi port configuration for Exynos Auto v9 SoC Chanho Park
2022-06-29 10:23       ` Chanho Park
2022-06-29 14:44   ` [PATCH v3 0/4] spi support " Mark Brown
2022-06-29 14:44     ` Mark Brown

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