From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 0/4] serial: omap: robustify for high speed transfers Date: Thu, 11 Feb 2016 13:00:50 -0800 Message-ID: <20160211210050.GY19432@atomide.com> References: <87lh7hrjsg.fsf@linutronix.de> <56A66FCB.1000507@hurleysoftware.com> <87y4b85onp.fsf@linutronix.de> <56B15603.80807@hurleysoftware.com> <87wpqbihel.fsf@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <87wpqbihel.fsf@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org To: John Ogness Cc: Peter Hurley , gregkh@linuxfoundation.org, vinod.koul@intel.com, dan.j.williams@intel.com, bigeasy@linutronix.de, nsekhar@ti.com, peter.ujfalusi@ti.com, dmaengine@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-serial@vger.kernel.org Hi, * John Ogness [160211 04:04]: > > At these speeds, nearly every DMA interrupt is accompanied by a spurious > UART interrupt. So, sadly, the interrupts are doubled. > > It is on my TODO list to verify if the spurious UART interrupts exactly > match the recently added [0] spurious interrupt detection in omap-intc. If you're seeing spurious interrupts you may want try adding a flush of posted write at the end of the 8250_omap interrupt handler. Basically read back some register from the 8250. This has fixed so far pretty much all the spurious IRQ issues for omaps using the drivers/irqchip/irq-omap-intc.c, meaning omap3 and am335x and ti81xx variants too most likely. Regards, Tony