diff options
Diffstat (limited to 'sound/soc/fsl/fsl_ssi.c')
| -rw-r--r-- | sound/soc/fsl/fsl_ssi.c | 60 |
1 files changed, 27 insertions, 33 deletions
diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c index 89df2d9f63d7d..0a648229e6430 100644 --- a/sound/soc/fsl/fsl_ssi.c +++ b/sound/soc/fsl/fsl_ssi.c @@ -1,34 +1,29 @@ -/* - * Freescale SSI ALSA SoC Digital Audio Interface (DAI) driver - * - * Author: Timur Tabi <timur@freescale.com> - * - * Copyright 2007-2010 Freescale Semiconductor, Inc. - * - * This file is licensed under the terms of the GNU General Public License - * version 2. This program is licensed "as is" without any warranty of any - * kind, whether express or implied. - * - * - * Some notes why imx-pcm-fiq is used instead of DMA on some boards: - * - * The i.MX SSI core has some nasty limitations in AC97 mode. While most - * sane processor vendors have a FIFO per AC97 slot, the i.MX has only - * one FIFO which combines all valid receive slots. We cannot even select - * which slots we want to receive. The WM9712 with which this driver - * was developed with always sends GPIO status data in slot 12 which - * we receive in our (PCM-) data stream. The only chance we have is to - * manually skip this data in the FIQ handler. With sampling rates different - * from 48000Hz not every frame has valid receive data, so the ratio - * between pcm data and GPIO status data changes. Our FIQ handler is not - * able to handle this, hence this driver only works with 48000Hz sampling - * rate. - * Reading and writing AC97 registers is another challenge. The core - * provides us status bits when the read register is updated with *another* - * value. When we read the same register two times (and the register still - * contains the same value) these status bits are not set. We work - * around this by not polling these bits but only wait a fixed delay. - */ +// SPDX-License-Identifier: GPL-2.0 +// +// Freescale SSI ALSA SoC Digital Audio Interface (DAI) driver +// +// Author: Timur Tabi <timur@freescale.com> +// +// Copyright 2007-2010 Freescale Semiconductor, Inc. +// +// Some notes why imx-pcm-fiq is used instead of DMA on some boards: +// +// The i.MX SSI core has some nasty limitations in AC97 mode. While most +// sane processor vendors have a FIFO per AC97 slot, the i.MX has only +// one FIFO which combines all valid receive slots. We cannot even select +// which slots we want to receive. The WM9712 with which this driver +// was developed with always sends GPIO status data in slot 12 which +// we receive in our (PCM-) data stream. The only chance we have is to +// manually skip this data in the FIQ handler. With sampling rates different +// from 48000Hz not every frame has valid receive data, so the ratio +// between pcm data and GPIO status data changes. Our FIQ handler is not +// able to handle this, hence this driver only works with 48000Hz sampling +// rate. +// Reading and writing AC97 registers is another challenge. The core +// provides us status bits when the read register is updated with *another* +// value. When we read the same register two times (and the register still +// contains the same value) these status bits are not set. We work +// around this by not polling these bits but only wait a fixed delay. #include <linux/init.h> #include <linux/io.h> @@ -385,8 +380,7 @@ static irqreturn_t fsl_ssi_isr(int irq, void *dev_id) { struct fsl_ssi *ssi = dev_id; struct regmap *regs = ssi->regs; - __be32 sisr; - __be32 sisr2; + u32 sisr, sisr2; regmap_read(regs, REG_SSI_SISR, &sisr); |