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=-19.0 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=unavailable 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 DC460C4338F for ; Mon, 16 Aug 2021 10:21:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C18DB61B3C for ; Mon, 16 Aug 2021 10:21:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235735AbhHPKVm (ORCPT ); Mon, 16 Aug 2021 06:21:42 -0400 Received: from foss.arm.com ([217.140.110.172]:42424 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229739AbhHPKUm (ORCPT ); Mon, 16 Aug 2021 06:20:42 -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 881666D; Mon, 16 Aug 2021 03:20:03 -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 96D4F3F40C; Mon, 16 Aug 2021 03:20:02 -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> <1d691b6b-dbc4-36b0-2e2a-beb95c4c9cb6@arm.com> <5b68f69c-f9cd-b0a4-45dd-d6db6d09fd65@gmail.com> From: Robin Murphy Message-ID: <0366a4e9-cc8a-499e-4b8a-bbd6fa088591@arm.com> Date: Mon, 16 Aug 2021 11:19:53 +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: <5b68f69c-f9cd-b0a4-45dd-d6db6d09fd65@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-08-16 08:42, Bing Fan wrote: > > At present, i think a focus of our discussion is whether this patch is > necessary. > > As for the other points you mentioned, I think they can be used as code > review comments. > > > Yes, as you described below, most dts files have only one interrupt, but > not all platforms are like this. > > The scene I'm encountering now is the latter: the interrupt lines of the > uart is connected to the gic separately > > so the dts should be define like this: > >                duart1: serial@5E139000 { >                         compatible = "arm,pl011", "arm,primecell"; >                         reg = <0x00 0x5E139000 0x0 0x1000>; >                         interrupts = , >                                 , >                                 , >                                 ; >                         clocks = <&sysclk>; >                         clock-names = "apb_pclk"; >                 }; Apologies for being unclear - the point I was implying is that of course you can do that in practice, but if you run that DTS through `make dtbs_check` it will fail. The binding needs extending to make it valid to specify more than one interrupt, and that's a separate patch and discussion in itself (simply increasing "maxitems" for the "interrupts" property is not enough to be robust). Robin. > The current tty-master code cannot meet this scenario, so I submitted > this patch. > > > > > > 在 2021/8/13 下午10:37, Robin Murphy 写道: >> [ +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); >>>