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Mon, 06 Jul 2020 07:43:16 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Mon, 6 Jul 2020 23:43:14 +0900 To: Kurt Kanzenbach Cc: Andy Shevchenko , Sergey Senozhatsky , Tony Lindgren , Petr Mladek , Raul Rangel , Sergey Senozhatsky , linux-kernel , Greg Kroah-Hartman , Andy Shevchenko , "S, Shirish" , Peter Zijlstra , John Ogness , Steven Rostedt Subject: Re: UART/TTY console deadlock Message-ID: <20200706144314.GB1485@jagdpanzerIV.localdomain> References: <20200630102141.GA11587@alley> <20200630105512.GA530@jagdpanzerIV.localdomain> <20200630122239.GD6173@alley> <20200630130534.GB145027@jagdpanzerIV.localdomain> <20200630180255.GD37466@atomide.com> <20200702051213.GB3450@jagdpanzerIV.localdomain> <20200702160514.GK37466@atomide.com> <20200703103241.GB182102@jagdpanzerIV.localdomain> <877dvg6ft6.fsf@kurt> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <877dvg6ft6.fsf@kurt> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/07/06 13:31), Kurt Kanzenbach wrote: > >> @@ -2275,6 +2275,7 @@ int serial8250_do_startup(struct uart_port *port) > >> > >> if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) { > >> unsigned char iir1; > >> + > >> /* > >> * Test for UARTs that do not reassert THRE when the > >> * transmitter is idle and the interrupt has already > >> @@ -2284,8 +2285,6 @@ int serial8250_do_startup(struct uart_port *port) > >> * allow register changes to become visible. > >> */ > >> spin_lock_irqsave(&port->lock, flags); > >> - if (up->port.irqflags & IRQF_SHARED) > >> - disable_irq_nosync(port->irq); > >> > >> wait_for_xmitr(up, UART_LSR_THRE); > >> serial_port_out_sync(port, UART_IER, UART_IER_THRI); > >> @@ -2297,8 +2296,6 @@ int serial8250_do_startup(struct uart_port *port) > >> iir = serial_port_in(port, UART_IIR); > >> serial_port_out(port, UART_IER, 0); > >> > >> - if (port->irqflags & IRQF_SHARED) > >> - enable_irq(port->irq); > >> spin_unlock_irqrestore(&port->lock, flags); > >> > >> /* > > > > ...which effectively is a revert of > > > > 768aec0b5bcc ("serial: 8250: fix shared interrupts issues with SMP and > > RT kernels") > > Please, don't revert that commit. I've faced the same issue as described > in the commit log. There is hardware available with shared UART > interrupt lines. Will this patch break that hardware? https://lore.kernel.org/lkml/20200702051213.GB3450@jagdpanzerIV.localdomain/ -ss