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 X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD74CC4338F for ; Fri, 13 Aug 2021 14:37:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 86BFE60C41 for ; Fri, 13 Aug 2021 14:37:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239515AbhHMOhu (ORCPT ); Fri, 13 Aug 2021 10:37:50 -0400 Received: from foss.arm.com ([217.140.110.172]:54144 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235396AbhHMOhu (ORCPT ); Fri, 13 Aug 2021 10:37:50 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1622C1042; Fri, 13 Aug 2021 07:37:23 -0700 (PDT) Received: from [10.57.36.146] (unknown [10.57.36.146]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3942E3F718; Fri, 13 Aug 2021 07:37:22 -0700 (PDT) Subject: Re: [PATCH v6] arm pl011 serial: support multi-irq request To: Bing Fan , gregkh@linuxfoundation.org, Russell King Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org References: <1628825490-18937-1-git-send-email-hptsfb@gmail.com> From: Robin Murphy Message-ID: <1d691b6b-dbc4-36b0-2e2a-beb95c4c9cb6@arm.com> Date: Fri, 13 Aug 2021 15:37:16 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <1628825490-18937-1-git-send-email-hptsfb@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org [ +Russell as the listed PL011 maintainer ] On 2021-08-13 04:31, Bing Fan wrote: > From: Bing Fan > > In order to make pl011 work better, multiple interrupts are > required, such as TXIM, RXIM, RTIM, error interrupt(FE/PE/BE/OE); > at the same time, pl011 to GIC does not merge the interrupt > lines(each serial-interrupt corresponding to different GIC hardware > interrupt), so need to enable and request multiple gic interrupt > numbers in the driver. > > Signed-off-by: Bing Fan > --- > drivers/tty/serial/amba-pl011.c | 39 +++++++++++++++++++++++++++++++-- > 1 file changed, 37 insertions(+), 2 deletions(-) > > diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c > index e14f3378b8a0..eaac3431459c 100644 > --- a/drivers/tty/serial/amba-pl011.c > +++ b/drivers/tty/serial/amba-pl011.c > @@ -1701,6 +1701,41 @@ static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h) > } > } > > +static void pl011_release_multi_irqs(struct uart_amba_port *uap, unsigned int max_cnt) > +{ > + struct amba_device *amba_dev = container_of(uap->port.dev, struct amba_device, dev); > + int i; > + > + for (i = 0; i < max_cnt; i++) > + if (amba_dev->irq[i]) > + free_irq(amba_dev->irq[i], uap); When you request the IRQs you break at the first zero, so this could potentially try to free IRQs that you haven't requested, if there happen to be any nonzero values beyond that. Maybe that can never happen, but there seems little need for deliberate inconsistency here. > +} > + > +static int pl011_allocate_multi_irqs(struct uart_amba_port *uap) > +{ > + int ret = 0; > + int i; > + unsigned int virq; > + struct amba_device *amba_dev = container_of(uap->port.dev, struct amba_device, dev); > + > + pl011_write(uap->im, uap, REG_IMSC); > + > + for (i = 0; i < AMBA_NR_IRQS; i++) { It's not clear where these extra IRQs are expected to come from given that the DT binding explicitly defines only one :/ > + virq = amba_dev->irq[i]; > + if (virq == 0) > + break; > + > + ret = request_irq(virq, pl011_int, IRQF_SHARED, dev_name(&amba_dev->dev), uap); Note that using dev_name() here technically breaks user ABI - scripts looking in /proc for an irq named "uart-pl011" will no longer find it. Furthermore, the "dev" cookie passed to request_irq is supposed to be globally unique, which "uap" isn't once you start registering it multiple times. If firmware did describe all the individual PL011 IRQ outputs on a system where they are muxed to the same physical IRQ anyway, you'd end up registering ambiguous IRQ actions here. Of course in practice you might still get away with that, but it is technically wrong. Robin. > + if (ret) { > + dev_err(uap->port.dev, "request %u interrupt failed\n", virq); > + pl011_release_multi_irqs(uap, i - 1); > + break; > + } > + } > + > + return ret; > +} > + > static int pl011_allocate_irq(struct uart_amba_port *uap) > { > pl011_write(uap->im, uap, REG_IMSC); > @@ -1753,7 +1788,7 @@ static int pl011_startup(struct uart_port *port) > if (retval) > goto clk_dis; > > - retval = pl011_allocate_irq(uap); > + retval = pl011_allocate_multi_irqs(uap); > if (retval) > goto clk_dis; > > @@ -1864,7 +1899,7 @@ static void pl011_shutdown(struct uart_port *port) > > pl011_dma_shutdown(uap); > > - free_irq(uap->port.irq, uap); > + pl011_release_multi_irqs(uap, AMBA_NR_IRQS); > > pl011_disable_uart(uap); > >