From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.134 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793147832; b=vV789GirLsBvSx8TTTNQiO8j2oGUn56AUk1F8LWKIA1Oy3tSARkYutM027H4E3pe/HLd EsTWO5K1CcBs5l8Rn8Bqe2EI8myjturqCWc9TrqWUmSeq9/5MLYWSV+fF8dHEXrTdLzy2 ER7DA4MA+h5UUUvz7m8LBq+wPKioyuUEGzEaHPY7gykHTN6SB1USnoLygtecNzHWRkjm6 nzqFuFe7ll0ETBecMaCme6xN4FvLzq5+pTzeozCZYKLnnXGB/sPL3YtxF0DW4P1if0txc b6eXUkWP90N1Mjbnk//AFdx1xl/0PUSpkWdY3DrW6ZKJGwxjkDzTrGvcd2SUpN3WH+w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793147832; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Cc:Subject:To:References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; bh=8PIwpydXKouR1joEe6jH+BAljrr4d+wB8gTbjsqTGKM=; b=fu5JEE6oQBeR0uE8f9dNlSoYz4d+ChLo5Ia/969NeKPvwypCC8GtIokhC45iPCORhG20 WzrZwPXL3KLxzL+dnTk/ZqiRo3whlZ94XBCK1vAFrBAo7P8dbrJEQ2eweLOKGmtTP4HZo jc074JZ9+HHsHz6mmPVtSuw9Dvav5L4MqdGvho1Y/LMx8Xa/KvaDlUtXQztlKYYTRMfxG of2OYvltWrs8z99UM+/De7wcDDc3zF5XC7mmS4CJ/y0L2VxZ2fFli4Pp+2Pn2m1vkcffY lPTDU+g+2eKt8L9Kft7/x5sxqL96Sn1iNl9SL/idyUr3GoOLC2z2PmAB6ubXC+ntORA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; arc=none smtp.remote-ip=95.215.58.134 Received: from mta1.migadu.com (out-134.mta1.migadu.com [95.215.58.134]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BA727606A31A for ; Wed, 28 Oct 2026 00:37:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org BA727606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=g6I0fGip7xLh8Q6oBq2a1cjMBbrnu+NWJFLuMFktGCs=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793147828; v=1; x=1793752628; b=a2y5PhjbmhP0ymGssWONsODfmaMtFLqpWuuqugLyHIlOajiJRhEINCBJK+bgJXCL1lIkazc+ sTmSKOibPsVt1M7x/gwZUlZaPJ1/oLU+SFB9+dGzrEcSBCr0o+Y+F3lB7/UzXJ6AJjnrhDbfG1B QoSZ1ncmOsZiKIXzjyiC7N0Q= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 54179253e2ede412; Wed, 28 Oct 2026 00:37:08 +0000 X-Mizu-Trace-ID: 54179253e2ede412 X-Migadu-Flow: FLOW_OUT Message-ID: <5ebe0445-a111-49a5-b9cf-0185d3c3f67b@linux.dev> Date: Wed, 28 Oct 2026 08:36:56 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: shawn.lin@linux.dev, linux-mmc@vger.kernel.org, Ulf Hansson , Adrian Hunter , Florian Fainelli , Wolfram Sang , Oleksij Rempel , linux-kernel@vger.kernel.org, Krzysztof Kozlowski Subject: Re: [PATCH v10 1/6] dt-bindings: mmc: Extend keep-power-in-suspend beyond SDIO To: Ulf Hansson , Kamal Dasu References: <20261027144051.249211-1-ulf.hansson@oss.qualcomm.com> <20261027144051.249211-2-ulf.hansson@oss.qualcomm.com> <583dc515-855c-48d6-aefb-abaef26b2564@linux.dev> From: Shawn Lin In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/10/28 星期三 3:46, Ulf Hansson 写道: > On Tue, Oct 27, 2026 at 4:02 PM Shawn Lin wrote: >> >> Hi >> >> 在 2026/10/27 星期二 22:40, Ulf Hansson 写道: >>> From: Kamal Dasu >>> >>> keep-power-in-suspend is currently documented as SDIO-only, but the >>> requirement it describes -- preserving card power across a >>> suspend/resume cycle -- applies just as well to any card type. Drop >>> the SDIO-only restriction so eMMC and SD platforms can use it too. >>> >> >> I don't see how SD could use it from the following patches. Perhaps we >> should still be more strict here to say SDIO and eMMC only, unless >> SD part is implemented later. > > I didn't have the bandwidth to implement this for SD at this very > moment, but the idea is to add it for SD too. > SDIO devices have a clear wake-on-host requirement, so keeping power on is reasonable. eMMC and SD are passively accessed devices, making this a pseudo-requirement under system freeze conditions until Broadcom chips changed the situation for eMMC. However, for the SD part, I doubt such a need exists. It would require dedicated ROM code support, and unlike eMMC, SD is not used as primary storage. Worse still, unlike eMMC and SDIO devices which are soldered down, vendors typically have an AVL to certify board-mounted components, while SD cards can be freely swapped. The compatibility of off-the-shelf SD cards is relatively poor, so I question whether there is a real-world scenario for SD cards here. If there is no such scenario, this is dead code. > That said, I was also thinking that maybe it would make sense to add a > sysfs node to allow the behavior to be controlled by userspace. > Thoughts? > Sure, regarding the sysfs node you mentioned, we already have mmc_caps2_set() exposed to userspace, and we can add MMC_CAP2_RESET_AT_RESUME support there >> >>> Signed-off-by: Kamal Dasu >>> Reviewed-by: Krzysztof Kozlowski >>> --- >>> .../devicetree/bindings/mmc/mmc-controller-common.yaml | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml b/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml >>> index 8b9b3b036129..2fc8e06d5ec9 100644 >>> --- a/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml >>> +++ b/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml >>> @@ -301,7 +301,7 @@ properties: >>> keep-power-in-suspend: >>> $ref: /schemas/types.yaml#/definitions/flag >>> description: >>> - SDIO only. Preserves card power during a suspend/resume cycle. >>> + Preserves card power during a suspend/resume cycle. >>> >>> wakeup-source: >>> $ref: /schemas/types.yaml#/definitions/flag >> > > Kind regards > Uffe