From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6BABA2DC763 for ; Mon, 12 Jan 2026 15:05:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768230321; cv=none; b=rU//V9K5GEWZKUTprUimhaOOjDtocAvKXYhvdYCAq7Y81OeKYhzMkSX3Mo2ophUuCNKfVo7BX3LJB8WSQI4IgYhnRrIA6K4gXxo1+J+UHIBKDuMu3lI6e+G4gRCvhAD3hwTumR0J0sy5HGMMF9S++4omOHErhTKUjGbF9ArBdvc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768230321; c=relaxed/simple; bh=6jBWdXZMhVkY69moXdQdlKCk8neTBul/f1U1dX6QdcY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sVDrAzn8A9GS+4qru9/KueN7Qv8U14PRI2+ucGPn7j0BaxRUNtdkCsD1NsuD18ExslubaSweNwljBdGXd1ffyKL32bFt/AlXYddvmkxwbTB5xG+gzCEKTldCxJ+9Hj/u3H8zVAcFmEGvPDl1Hxdne8HdUZ+Uh3eazS9jwb8DGbQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=si0QLla2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="si0QLla2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69AE4C16AAE; Mon, 12 Jan 2026 15:05:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768230321; bh=6jBWdXZMhVkY69moXdQdlKCk8neTBul/f1U1dX6QdcY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=si0QLla2TbfkKpncQ2x1ma4Ue8rahnpJtCYaQBXxw96sOOwFCFzvzESI7RuhAZ6L1 0xCNlRNiZS4XVCqjFLxi1nxfPsys+1jDhr6yZY95Ah15o3/uAE/dpcNwSoAlGWPgoY nEEZMjh0JT/Kzs0I7Sm3zsR2+9pJx+Cw21TZKh+QpDGnMImJNOOkkJXm2ays3DSjWo lQIxB9WdKLZEQ01bAAi6n8/lv8INnr6D+um3D5SQVrUaRJ4aQx1zpKf0rrqCwg12Vr 2+JkNUV580ZujU+jdlEOWpbiIXrVEGpf/yxl00j5+DZ7P49am8kT/HzdBjj5KqhVMx 4kW648Avbeh8g== Message-ID: <698e738b-5ad2-4c03-ad5c-837123872a10@kernel.org> Date: Mon, 12 Jan 2026 16:05:18 +0100 Precedence: bulk X-Mailing-List: linux-ide@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/6] ata: libata-sata: Improve link_power_management_supported sysfs attribute To: Niklas Cassel Cc: linux-ide@vger.kernel.org, wolf@yoxt.cc References: <20260112122044.143637-8-cassel@kernel.org> <20260112122044.143637-11-cassel@kernel.org> <5b945fcf-059d-409c-9475-630483c14a5e@kernel.org> Content-Language: en-US From: Damien Le Moal Organization: Western Digital Research In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/12/26 15:39, Niklas Cassel wrote: > I'm not sure if we should set sysfs attribute > link_power_management_supported == false if ATA_LFLAG_NO_LPM is set > (Currently we don't). Because if so, the sysfs supported attribute could > potentially change value during runtime, isn't it supposed to be static? > > If we really want to, I guess we could do something like: > > diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c > index 04e1e774645e..1134943f49ae 100644 > --- a/drivers/ata/libata-sata.c > +++ b/drivers/ata/libata-sata.c > @@ -913,6 +913,8 @@ static bool ata_scsi_lpm_supported(struct ata_port *ap) > return false; > > ata_for_each_link(link, ap, EDGE) { > + if (link->flags & ATA_LFLAG_NO_LPM) > + return false; Yeah, I think we need this. NO_LPM == max power, but cannot be changed. That's the same as for external ports. So we should report not supported so that userspace cannot change it. > ata_for_each_dev(dev, &ap->link, ENABLED) { > if (dev->quirks & ATA_QUIRK_NOLPM) > return false; > > > But if so, that should probably be a different patch. > > This patch was mainly to stop lying to the user that dummy ports could > change/set lpm_policy. > > > For the record, not all libata drivers provide a .set_lpm() callback. > > Right now, the only drivers providing it are: > ata_piix.c: .set_lpm = piix_sidpr_set_lpm, > libahci.c: .set_lpm = ahci_set_lpm, > > > Kind regards, > Niklas -- Damien Le Moal Western Digital Research