From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 96F5E606A335 for ; Fri, 13 Nov 2026 21:03:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=1uKMCZuL; dkim=fail reason="signature verification failed" (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.a=rsa-sha256 header.s=dkim header.b=NsozwJp3 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=bqzJuH6BYeGzsrfSJVl2VB9oN3zz1SPOKfP0ZsOtE/A=; b=1uKMCZuL97Fq0dpN41ZRLqSn2j Ly/jn2IjKCZN+x4y2+kQN54skJNv7tMDyJhHLiiBaOi8y+o+4bhNQjP/FEdZzcqCalcwtJdZPRw7R KDq7uztyk3lCmaiWAiGrCDyvjeQTCB1lXXjy216846/sqJWQlMDWGDGO+ZYt5kzIOKjkYfgixSFhj 33mRRanhQbLNsDahZkpE/V23hBZS45XAzksTyqpu34U/6qvm2GrVJQx9U2dc11Ds2TNkkhVzZ1FyX /zliWMqlZISOcAGMixPC/m6XWB+bSd9R+8Hj8GmFhzwT2YojaTFPZRXXmRpxtcPcoGhBJwPd4Y3wt WXVf390w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRyRA-0000000EVsO-1QOE; Fri, 13 Nov 2026 21:03:56 +0000 Received: from smtpout-03.galae.net ([185.246.85.4]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRyR6-0000000EVro-0guv for linux-i3c@lists.infradead.org; Fri, 13 Nov 2026 21:03:54 +0000 Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id 4DC6A4E415B5 for ; Fri, 13 Nov 2026 21:03:47 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 1ADDD60015; Fri, 13 Nov 2026 21:03:47 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 4992B11BC1337; Fri, 13 Nov 2026 22:03:44 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1794603826; h=from:subject:date:message-id:to:cc:mime-version:content-type: in-reply-to:references; bh=ck6Xb76oYj2opbdzc1LWSQxElh6ruQvZWniy29JDCHo=; b=NsozwJp3th5HnfhRbz8Jgo4qJEtdfaS8tRtF4QCFsJsxKpEqe9PeXXadPfy/CnramYkmcs EjIpm+NpWxD4yxJ/S9aLJuXvUinJcJ9V1SDNoHlNNbXHorWPXQiOK4F6qjlliQP/tJWBVn cu/jzw/fYLy9VMeviu9bafjzPaYESM6tOGbWd3nIgLP1HjtU/4xNzQZgERanfbq7Z2jkaG wiN/EPrg8Vhfiz/VeKMEKR1MwVtj1Quc5n1gFZTfHU2l+xB9JNnWus0j7W0fk7FCb7uuws v+OaWS6PmGgPdwRfjYF5nQtOx+tPuGEKC+Cpada2LmK0Nv1leTLGyHO2/KvJyg== Date: Fri, 13 Nov 2026 22:03:43 +0100 From: Alexandre Belloni To: "Pathak, Asutosh" Cc: samagazaryan@google.com, Frank.Li@nxp.com, meaganlloyd@linux.microsoft.com, linux-i3c@lists.infradead.org Subject: Re: [PATCH v5 0/5] i3c: add i3cdev module to expose i3c dev in /dev Message-ID: <202611132103434b1803e4@mail.local> References: <298e818d-90b5-4231-bbc6-ef840c0691ca@linux.intel.com> X-Archived-By: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <298e818d-90b5-4231-bbc6-ef840c0691ca@linux.intel.com> X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261113_130352_370425_D897A0BA X-CRM114-Status: GOOD ( 16.45 ) X-Spam-Score: -2.1 (--) X-BeenThere: linux-i3c@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-i3c" X-Spam-Status: No, score=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 13/11/2026 10:11:36-0800, Pathak, Asutosh wrote: > Hi Sam, > > Alexandre pointed me at this series. I'm working on a driver for the USB-I3C > device class (USB class 0x3C) - a USB device that acts as an I3C controller, > with a host-side tool (OpenIPC) that drives the bus from userspace. The master > part registers normally, so its targets would show up as i3cdev nodes and we'd > rather use I3C_IOC_XFER than carry our own ioctls. So +1 on the direction. > > A few things we need that the current UAPI doesn't cover yet - wanted to raise > them now rather than after it lands: > > 1. IBIs to userspace. Our main use case is reacting to target interrupts, but > i3cdev is transfer-only today. We'd need a way to get IBIs (and ideally > hot-join) delivered to the fd - poll()/read() of an event, or similar. > This is the big one for us. > > 2. Larger transfers. len/actual_len are u16 and I3C_IOC_XFER caps the count. > Our bulk flows go past 64K, so we'd want either a larger width or a > documented way to split without dropping the bus lock mid-sequence. > Hum, seeing 1 and 2 now, shouldn't you rather have an actual kernel driver to handle the devices present on the i3c bus? What are those devices? > 3. Explicit opt-in over auto-attach. For bring-up/validation we don't want a > node appearing just because a driver got unbound - Meagan's driver_override > approach fits us better, and it also answers Andy's HW-damage concern. > > 4. CCCs from userspace. The union { rnw; cmd; } looks like it's meant for this - > just confirming direct/broadcast CCCs are in scope, since our tooling needs > them. > Which CCCs do you need? -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com -- linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c