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From: Sylwester Nawrocki <s.nawrocki@samsung.com>
To: Michael Turquette <mturquette@baylibre.com>,
	Andi Shyti <andi.shyti@samsung.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Kukjin Kim <kgene@kernel.org>,
	Krzysztof Kozlowski <k.kozlowski@samsung.com>,
	Mark Brown <broonie@kernel.org>,
	Tomasz Figa <tomasz.figa@gmail.com>,
	Stephen Boyd <sboyd@codeaurora.org>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Jaehoon Chung <jh80.chung@samsung.com>,
	linux-clk@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-spi@vger.kernel.org,
	Andi Shyti <andi@etezian.org>
Subject: Re: [PATCH v2 6/7] spi: s3c64xx: restore removed comments
Date: Mon, 11 Jul 2016 12:33:42 +0200
Message-ID: <57837606.8050906@samsung.com> (raw)
In-Reply-To: <146799464881.73491.7507792367941552864@resonance>

On 07/08/2016 06:17 PM, Michael Turquette wrote:
> Quoting Andi Shyti (2016-07-08 07:46:40)

>> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
>> index 6da663f..32b66f0 100644
>> --- a/drivers/spi/spi-s3c64xx.c
>> +++ b/drivers/spi/spi-s3c64xx.c
>> @@ -639,6 +639,7 @@ static void s3c64xx_spi_config(struct s3c64xx_spi_driver_data *sdd)
>>         writel(val, regs + S3C64XX_SPI_MODE_CFG);
>>  
>>         if (sdd->port_conf->clk_from_cmu) {
>> +               /* There is half-multiplier before the SPI */
>>                 clk_set_rate(sdd->src_clk, sdd->cur_speed * 2);
> 
> Just a small comment, but if the fixed-factor divide-by-two clock was
> modeled in Linux, then this driver could call clk_set_rate on that clock
> with the "correct" rate.
> 
> I guess that this driver would be the provider of that clock?

Good point, however I'm not sure if it is worth to model this divider
with a clk object.  It is an internal divider and the clock it provides
is only used internally within the SPI controller.  Thus the spi-s3c64xx
driver would be provider on the only consumer of this clock.

Additionally, the "There is half-multiplier before the SPI" comment
seems to be obfuscating how the hardware really looks like to me.
It talks about multiplier (which reminds me of PLLs with a divider
in the feedback loop) while there is a simple divider which should
be considered as an integral part of the controller IP block.

While we are at it, I'd propose to change this comment to something
like:

/* The SCLK_SPI clock is divided internally by 2 */

  parent reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-08 14:46 [PATCH v2 0/7] spi s3c64xx ioclk handling Andi Shyti
2016-07-08 14:46 ` [PATCH v2 1/7] bindings: spi-samsung: add exynos5433 spi compatible Andi Shyti
2016-07-08 20:23   ` Krzysztof Kozlowski
2016-07-11 10:49   ` Sylwester Nawrocki
2016-07-14 16:33   ` Applied "spi: s3c64xx: add exynos5433 spi compatible" to the spi tree Mark Brown
2016-07-08 14:46 ` [PATCH v2 2/7] bindings: spi-samsung: document the clocks and the clock-name property Andi Shyti
2016-07-08 14:46 ` [PATCH v2 3/7] spi: s3c64xx: rename goto labels to meaningful names Andi Shyti
2016-07-14 16:32   ` Applied "spi: s3c64xx: rename goto labels to meaningful names" to the spi tree Mark Brown
2016-07-08 14:46 ` [PATCH v2 4/7] spi: s3c64xx: use error code from clk_prepare_enable() Andi Shyti
2016-07-08 20:33   ` Krzysztof Kozlowski
2016-07-14 16:32   ` Applied "spi: s3c64xx: use error code from clk_prepare_enable()" to the spi tree Mark Brown
2016-07-08 14:46 ` [PATCH v2 5/7] spi: s3c64xx: add exynos5433 compatible for ioclk handling Andi Shyti
2016-07-08 16:13   ` Michael Turquette
2016-07-08 16:31     ` Andi Shyti
2016-07-08 20:39   ` Krzysztof Kozlowski
2016-07-14 16:32   ` Applied "spi: s3c64xx: add Exynos5433 compatible for ioclk handling" to the spi tree Mark Brown
2016-07-08 14:46 ` [PATCH v2 6/7] spi: s3c64xx: restore removed comments Andi Shyti
2016-07-08 16:17   ` Michael Turquette
2016-07-08 16:35     ` Andi Shyti
2016-07-11 10:33     ` Sylwester Nawrocki [this message]
2016-07-11 22:17       ` Michael Turquette
2016-07-12 12:16         ` Sylwester Nawrocki
2016-07-12  6:54       ` [PATCH v3 " Andi Shyti
2016-07-12  8:22         ` Mark Brown
2016-07-12  8:25           ` Andi Shyti
2016-07-12  9:00             ` Mark Brown
2016-07-12 18:07         ` Michael Turquette
2016-07-14 16:32         ` Applied "spi: s3c64xx: restore removed comments" to the spi tree Mark Brown
2016-07-08 20:35   ` [PATCH v2 6/7] spi: s3c64xx: restore removed comments Krzysztof Kozlowski
2016-07-08 14:46 ` [PATCH v2 7/7] clk: exynos5433: remove CLK_IGNORE_UNUSED flag from SPI clocks Andi Shyti
2016-07-11 10:58   ` Sylwester Nawrocki
2016-07-08 16:21 ` [PATCH v2 0/7] spi s3c64xx ioclk handling Michael Turquette
2016-07-11  2:36 [PATCH v3] bindings: spi-samsung: document the clocks and the clock-name property Andi Shyti
2016-07-14 16:32 ` Applied "spi: s3c64xx: document the clocks and the clock-name property" to the spi tree Mark Brown

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