From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751159AbdAPJZl (ORCPT ); Mon, 16 Jan 2017 04:25:41 -0500 Received: from mga02.intel.com ([134.134.136.20]:42982 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750874AbdAPJYz (ORCPT ); Mon, 16 Jan 2017 04:24:55 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,238,1477983600"; d="scan'208";a="1083509421" Message-ID: <1484558690.2133.132.camel@linux.intel.com> Subject: Re: [PATCH 1/2] spi: pxa2xx: Prepare for edge-triggered interrupts From: Andy Shevchenko To: Jan Kiszka , linux-arm-kernel@lists.infradead.org Cc: Daniel Mack , Haojian Zhuang , Robert Jarzmik , linux-kernel@vger.kernel.org, Mika Westerberg , Jarkko Nikula , Sascha Weisenberger Date: Mon, 16 Jan 2017 11:24:50 +0200 In-Reply-To: <6fe26505e67790b27eed28fd7451b51e70b7e8ba.1484557560.git.jan.kiszka@siemens.com> References: <6fe26505e67790b27eed28fd7451b51e70b7e8ba.1484557560.git.jan.kiszka@siemens.com> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.3-1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2017-01-16 at 10:05 +0100, Jan Kiszka wrote: > When using the a device with edge-triggered interrupts, such as MSIs, > the interrupt handler has to ensure that there is a point in time > during > its execution where all interrupts sources are silent so that a new > event can trigger a new interrupt again. > > This is achieved here by looping over SSSR evaluation. We need to take > into account that SSCR1 may be changed by the transfer handler, thus > we > need to redo the mask calculation, at least regarding the volatile > interrupt enable bit (TIE). Could you split this to two patches, one just move the code under question to a helper function (no functional change), the other does what you state in commit message here? > > Signed-off-by: Jan Kiszka > --- >  drivers/spi/spi-pxa2xx.c | 50 +++++++++++++++++++++++++++---------- > ----------- >  1 file changed, 28 insertions(+), 22 deletions(-) > > diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c > index dd7b5b4..24bf549 100644 > --- a/drivers/spi/spi-pxa2xx.c > +++ b/drivers/spi/spi-pxa2xx.c > @@ -737,6 +737,7 @@ static irqreturn_t ssp_int(int irq, void *dev_id) >   struct driver_data *drv_data = dev_id; >   u32 sccr1_reg; >   u32 mask = drv_data->mask_sr; > + irqreturn_t ret = IRQ_NONE; >   u32 status; >   >   /* > @@ -760,37 +761,42 @@ static irqreturn_t ssp_int(int irq, void > *dev_id) >   >   sccr1_reg = pxa2xx_spi_read(drv_data, SSCR1); >   > - /* Ignore possible writes if we don't need to write */ > - if (!(sccr1_reg & SSCR1_TIE)) > - mask &= ~SSSR_TFS; > - >   /* Ignore RX timeout interrupt if it is disabled */ >   if (!(sccr1_reg & SSCR1_TINTE)) >   mask &= ~SSSR_TINT; >   > - if (!(status & mask)) > - return IRQ_NONE; > + while (1) { > + /* Ignore possible writes if we don't need to write > */ > + if (!(sccr1_reg & SSCR1_TIE)) > + mask &= ~SSSR_TFS; >   > - if (!drv_data->master->cur_msg) { > + if (!(status & mask)) > + return ret; >   > - pxa2xx_spi_write(drv_data, SSCR0, > -  pxa2xx_spi_read(drv_data, SSCR0) > -  & ~SSCR0_SSE); > - pxa2xx_spi_write(drv_data, SSCR1, > -  pxa2xx_spi_read(drv_data, SSCR1) > -  & ~drv_data->int_cr1); > - if (!pxa25x_ssp_comp(drv_data)) > - pxa2xx_spi_write(drv_data, SSTO, 0); > - write_SSSR_CS(drv_data, drv_data->clear_sr); > + if (!drv_data->master->cur_msg) { >   > - dev_err(&drv_data->pdev->dev, > - "bad message state in interrupt handler\n"); > + pxa2xx_spi_write(drv_data, SSCR0, > +  pxa2xx_spi_read(drv_data, > SSCR0) > +  & ~SSCR0_SSE); > + pxa2xx_spi_write(drv_data, SSCR1, > +  pxa2xx_spi_read(drv_data, > SSCR1) > +  & ~drv_data->int_cr1); > + if (!pxa25x_ssp_comp(drv_data)) > + pxa2xx_spi_write(drv_data, SSTO, 0); > + write_SSSR_CS(drv_data, drv_data->clear_sr); >   > - /* Never fail */ > - return IRQ_HANDLED; > - } > + dev_err(&drv_data->pdev->dev, > + "bad message state in interrupt > handler\n"); >   > - return drv_data->transfer_handler(drv_data); > + /* Never fail */ > + return IRQ_HANDLED; > + } > + > + ret |= drv_data->transfer_handler(drv_data); > + > + status = pxa2xx_spi_read(drv_data, SSSR); > + sccr1_reg = pxa2xx_spi_read(drv_data, SSCR1); > + } >  } >   >  /* -- Andy Shevchenko Intel Finland Oy