From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Andi Shyti <andi.shyti@kernel.org>,
linux-renesas-soc@vger.kernel.org, linux-i2c@vger.kernel.org,
linux-sh@vger.kernel.org
Subject: Re: [PATCH v2] i2c: sh_mobile: Switch R-Mobile A1/APE6 and SH-Mobile AG5 to new frequency calculation
Date: Wed, 31 Jan 2024 21:34:56 +0100 [thread overview]
Message-ID: <Zbqu8K3gBth83YBV@shikoro> (raw)
In-Reply-To: <93f3b97c20164510ed80928500a8d443d7e23adb.1706717315.git.geert+renesas@glider.be>
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On Wed, Jan 31, 2024 at 05:09:30PM +0100, Geert Uytterhoeven wrote:
> Switch the R-Mobile A1, R-Mobile APE6, and SH-Mobile AG5 SoCs to the new
> frequency calculation formula, to (a) avoid running the I2C bus too fast,
> and (b) bring the low/high ratio closer to the recommended ratio 5/4.
>
> As this makes fast_clock_dt_config and v2_freq_calc_dt_config identical,
> merge them into a single fast_clock_dt_config.
>
> Legacy SH users (sh7343, sh7366, and sh772[234]) are left alone, and
> still use the old formula.
>
> Measurement results on R-Mobile APE6 and SH-Mobile AG5 (fck=104 MHz,
> clks_per_count=2):
> 100 kHz: 106 kHz LH=1.12 before, 99.6 kHz L/H=1.22 after
> 400 kHz: 384 kHz LH=1.67 before, 392 kHz L/H=1.27 after
>
> Measurement results on R-Mobile A1 (fck=49.5 MHz, clks_per_count=1):
> 100 kHz: 106 kHz L/H=1.09 before, 99.6 kHz L/H=1.20 after
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
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next prev parent reply other threads:[~2024-01-31 20:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-31 16:09 [PATCH v2] i2c: sh_mobile: Switch R-Mobile A1/APE6 and SH-Mobile AG5 to new frequency calculation Geert Uytterhoeven
2024-01-31 20:34 ` Wolfram Sang [this message]
2024-01-31 22:55 ` Andi Shyti
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