From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8D14FC4167B for ; Mon, 27 Nov 2023 18:33:24 +0000 (UTC) Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id C1020A4C; Mon, 27 Nov 2023 19:33:11 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz C1020A4C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1701110001; bh=ii26YioRm1dVaNmafDquet6vORNU5vVrSjgLkugEVf4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-Id: List-Archive:List-Help:List-Owner:List-Post:List-Subscribe: List-Unsubscribe:From; b=TUd6Plj2SoaoBez9Cid2lelb8KjHOWh6qRAnlgQPr+q1ZUjiCkftf5EH2/687amRN uTwnAd+yQdrdrGp+etKEBYJWebcW0yGUeMi3mEWY/RZ/GAWwUgeQNkKYEJ44FLpZF8 HHgIzHiCKYKRDV5MoKywBCNylI+00I6W2JscKqFs= Received: by alsa1.perex.cz (Postfix, from userid 50401) id BA358F80580; Mon, 27 Nov 2023 19:32:50 +0100 (CET) Received: from mailman-core.alsa-project.org (mailman-core.alsa-project.org [10.254.200.10]) by alsa1.perex.cz (Postfix) with ESMTP id 4462AF80571; Mon, 27 Nov 2023 19:32:50 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 4329FF801D5; Mon, 27 Nov 2023 19:32:45 +0100 (CET) Received: from m.b4.vu (m.b4.vu [203.16.231.148]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 6B0F4F800F5 for ; Mon, 27 Nov 2023 19:32:32 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 6B0F4F800F5 Received: by m.b4.vu (Postfix, from userid 1000) id 5CE5A604F550; Tue, 28 Nov 2023 05:02:26 +1030 (ACDT) Date: Tue, 28 Nov 2023 05:02:26 +1030 From: "Geoffrey D. Bennett" To: Takashi Iwai Cc: Jaroslav Kysela , Takashi Iwai , alsa-devel@alsa-project.org, linux-sound@vger.kernel.org Subject: Re: [PATCH RFC v2] ALSA: scarlett2: Add ioctls for user-space access Message-ID: References: <76c1526d-78be-92d2-cf2b-148278394575@perex.cz> <123242ed-c343-dab8-fed1-9f5d2da44d7a@perex.cz> <87edhtn0r2.wl-tiwai@suse.de> <871qcfqnht.wl-tiwai@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <871qcfqnht.wl-tiwai@suse.de> Message-ID-Hash: CYHPVIXRSDADN4K6BYV2GKSOXZJV6YTQ X-Message-ID-Hash: CYHPVIXRSDADN4K6BYV2GKSOXZJV6YTQ X-MailFrom: g@b4.vu X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.9 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Hi Takashi, On Fri, Nov 24, 2023 at 02:39:26PM +0100, Takashi Iwai wrote: > On Sun, 19 Nov 2023 18:35:27 +0100, > Geoffrey D. Bennett wrote: > > > > Hi Jaroslav, Takashi, > > > > I took your feedback onboard about not providing generic access to the > > scarlett2_usb() function from user-space. > > > > After a few iterations, I've come up with this hwdep interface to > > support reset-to-factory-defaults, reset-to-factory-firmware, and > > firmware-update in a safe way: > > > > -----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<----- > > > > /* Get protocol version */ > > #define SCARLETT2_IOCTL_PVERSION _IOR('S', 0x60, int) > > > > /* Reboot */ > > #define SCARLETT2_IOCTL_REBOOT _IO('S', 0x61) > > > > /* Select flash segment */ > > #define SCARLETT2_SEGMENT_ID_SETTINGS 0 > > #define SCARLETT2_SEGMENT_ID_FIRMWARE 1 > > #define SCARLETT2_SEGMENT_ID_COUNT 2 > > > > #define SCARLETT2_IOCTL_SELECT_FLASH_SEGMENT _IOW('S', 0x62, int) > > > > /* Erase selected flash segment */ > > #define SCARLETT2_IOCTL_ERASE_FLASH_SEGMENT _IO('S', 0x63) > > > > /* Get selected flash segment erase progress > > * 1 through to num_blocks, or 255 for complete > > */ > > struct scarlett2_flash_segment_erase_progress { > > unsigned char progress; > > unsigned char num_blocks; > > }; > > #define SCARLETT2_IOCTL_GET_ERASE_PROGRESS \ > > _IOR('S', 0x64, struct scarlett2_flash_segment_erase_progress) > > > > -----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<----- > > > > Does that look reasonable to you? > > > > Broadly, it's used like this: > > > > Reset to factory default configuration: > > > > - ioctl select_flash_segment SCARLETT2_SEGMENT_ID_SETTINGS > > - ioctl erase_flash_segment > > - ioctl get_erase_progress (optional) > > So the erase operation is asynchronous? This sounds a bit dangerous. > Will the driver block further conflicting operations until the erase > finishes? Yes it is asynchronous. I've made it so that it's not dangerous by locking out any conflicting operations: - Mixer operations that require device access return EBUSY - The hwdep is marked as exclusive so other processes can't use it - Subsequent hwdep operations (if get_erase_progress wasn't called) will block until the erase is complete > > Erase firmware (reverts to factory firmware which is stored in a > > different flash segment, inaccessible from these ioctls): > > > > - ioctl select_flash_segment SCARLETT2_SEGMENT_ID_FIRMWARE > > - ioctl erase_flash_segment > > - ioctl get_erase_progress (optional) > > > > Upload new firmware: > > > > - write() <- a bunch of these, only permitted after the previous erase > > step was completed > > The write op must accept partial writes, and it becomes cumbersome. > Can it be a one-shot ioctl, too? I considered one-shot ioctls, but as the erase & write operations take some seconds, then it is not possible to provide feedback to the end-user while the erase & write operations happen. > > On completion: > > > > - ioctl reboot > > > > To confirm that this interface is sufficient, I have implemented it in > > the scarlett2 driver and written a user-space utility which can > > perform all the above operations. > > > > I will clean up the implementation a bit and then submit for review; > > just wanted to share the interface first in case you have any comments > > at this point. > > IMO, from the user POV, it's easier to have per-purpose ioctls, > instead of combining multiple ioctl sequences. Of course, it won't > scale too much, but for the limited number of operations, it's > clearer. > > That is, we can provide just a few ioctls for reset-to-factory, > reset-to-something-else, and update. > > But, if you need asynchronous operations inevitably by some reason, > it's a different story, though. Just to provide progress feedback to the end-user. I've written the CLI tool using the proposed ioctl interface, and it works nicely: https://github.com/geoffreybennett/scarlett2 [g@fedora ~]$ time scarlett2 update Selected device Scarlett 4th Gen Solo Found firmware version 2115 for Scarlett 4th Gen Solo: /usr/lib/firmware/scarlett2/scarlett2-1235-8218-2115.bin Updating Scarlett 4th Gen Solo from firmware version 1974 to 2115 Resetting configuration to factory default... Erase progress: Done! Erasing upgrade firmware... Erase progress: Done! Firmware write progress: Done! Rebooting interface... real 0m5.919s user 0m0.007s sys 0m0.034s The user experience would not be as nice with one-shot ioctls. And using ioctls which block for a long time would make using them from the GUI https://github.com/geoffreybennett/alsa-scarlett-gui/ rather awkward. None of the other operations on the interface block for an appreciable amount of time. I've got a first draft of firmware update and Scarlett 4th Gen support that I am sharing with others to test now. It's 48 commits, divided into: - 5 commits to add extra checks that are missing - 5 commits for firmware management - 20 commits refactoring the existing driver to allow Scarlett 4th Gen support to be added - 18 commits adding the support (although the underlying Gen 4 protocol is the same as the other series, there are many new different types of controls) I've put those commits on this branch: https://github.com/geoffreybennett/scarlett-gen2/tree/scarlett-gen4 Do you want me to share all 48 commits on the mailing list at once? Or maybe just the first 5+5 commits for now and the rest after I get some feedback from others? Thanks, Geoffrey.