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From: Stephan Gerhold <stephan.gerhold@linaro.org>
To: Linus Walleij <linusw@kernel.org>
Cc: u-boot@lists.u-boot-project.org, Tom Rini <trini@konsulko.com>,
	Stefan Hansson <newbyte@postmarketos.org>
Subject: Re: [PATCH v5 03/13] mmc: arm_pl180: Gate idle card clocks
Date: Mon, 24 Aug 2026 15:25:31 +0200	[thread overview]
Message-ID: <aoxGSzMOF1o75XpH@linaro.org> (raw)
In-Reply-To: <20260823-ux500-external-sdcard-v5-3-07ca794e2b94@kernel.org>

On Sun, Aug 23, 2026 at 10:39:22PM +0200, Linus Walleij wrote:
> The MMC core uses mmc->clk_disable to request that the card clock is
> stopped, but the PL180 driver leaves SDI_CLKCR_CLKEN unchanged. This can
> leave inactive hosts driving their card clocks.
> 
> Honor clk_disable when programming the clock control register. Also enable
> the PL180 power-save mode so the clock stops automatically while the bus is
> idle.

I'm not so sure about enabling PWRSAV, given that even Linux keeps that
disabled. See mmci_set_clkreg():

		clk |= MCI_CLK_ENABLE;
		/* This hasn't proven to be worthwhile */
		/* clk |= MCI_CLK_PWRSAVE; */

Which is BTW your own change from 2009. :-)
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=a6a6464a0ecd20c5f1594a4fe5b24af6181b7366

The clk_disable part looks fine to me.

Thanks,
Stephan

  reply	other threads:[~2026-08-24 13:25 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-23 20:39 [PATCH v5 00/13] arm: u8500: Enable upstream DT based SD card boot Linus Walleij
2026-08-23 20:39 ` [PATCH v5 01/13] pinctrl: Add compact Nomadik pin controller Linus Walleij
2026-08-24 13:17   ` Stephan Gerhold
2026-08-23 20:39 ` [PATCH v5 02/13] mmc: arm_pl180: Configure Ux500 signal direction Linus Walleij
2026-08-23 20:39 ` [PATCH v5 03/13] mmc: arm_pl180: Gate idle card clocks Linus Walleij
2026-08-24 13:25   ` Stephan Gerhold [this message]
2026-08-24 19:50     ` Linus Walleij
2026-08-23 20:39 ` [PATCH v5 04/13] power: regulator: Add driver voltage clamp callback Linus Walleij
2026-08-23 20:39 ` [PATCH v5 05/13] mmc: arm_pl180: Set initial supply voltages Linus Walleij
2026-08-23 20:39 ` [PATCH v5 06/13] mmc: arm_pl180: Power down card supplies at OS handoff Linus Walleij
2026-08-24 13:30   ` Stephan Gerhold
2026-08-24 20:01     ` Linus Walleij
2026-08-25  7:43       ` Stephan Gerhold
2026-08-23 20:39 ` [PATCH v5 07/13] power: regulator: Add AB8500 AUX3 support Linus Walleij
2026-08-24 13:45   ` Stephan Gerhold
2026-08-24 20:04     ` Linus Walleij
2026-08-23 20:39 ` [PATCH v5 08/13] arm: u8500: Enable SD card regulators Linus Walleij
2026-08-23 20:39 ` [PATCH v5 09/13] configs: stemmy: Boot EFI from external SD card Linus Walleij
2026-08-24 13:46   ` Stephan Gerhold
2026-08-23 20:39 ` [PATCH v5 10/13] arm: u8500: Switch Stemmy to upstream Janice device tree Linus Walleij
2026-08-24 13:55   ` Stephan Gerhold
2026-08-24 20:21     ` Linus Walleij
2026-08-23 20:39 ` [PATCH v5 11/13] ARM: dts: ux500: Make panel regulators have unique names Linus Walleij
2026-08-23 20:39 ` [PATCH v5 12/13] ARM: dts: ux500: Harmonize GPIO key names Linus Walleij
2026-08-23 20:39 ` [PATCH v5 13/13] arm: u8500: Package Stemmy device trees in FIT Linus Walleij
2026-08-24 13:59   ` Stephan Gerhold

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