Re: [RFC PATCH 09/14] ASoC: qcom: Add ability to handle interrupts per dma channel

From: Kenneth Westfield
Date: Sat May 02 2015 - 20:00:36 EST


On Thu, Apr 30, 2015 at 06:17:42PM +0100, Srinivas Kandagatla wrote:
> This patch adds ablity to lpass driver to handle interrupt per dma
> channel. Without this patch its not possible to use multipl ports on the
> lpass.

> diff --git a/sound/soc/qcom/lpass-platform.c b/sound/soc/qcom/lpass-platform.c
> index 8ab0ac1..c5907d5 100644
> --- a/sound/soc/qcom/lpass-platform.c
> +++ b/sound/soc/qcom/lpass-platform.c

> -static irqreturn_t lpass_platform_lpaif_irq(int irq, void *data)
> +static irqreturn_t lpass_dma_interrupt_handler(
> + struct snd_pcm_substream *substream,
> + struct lpass_data *drvdata,
> + int chan, u32 interrupts)
> {
> - struct snd_pcm_substream *substream = data;
> struct snd_soc_pcm_runtime *soc_runtime = substream->private_data;
> - struct lpass_data *drvdata =
> - snd_soc_platform_get_drvdata(soc_runtime->platform);
> struct lpass_variant *v = drvdata->variant;
> - struct lpass_pcm_data *pcm_data = snd_soc_pcm_get_drvdata(soc_runtime);
> - unsigned int interrupts;
> irqreturn_t ret = IRQ_NONE;
> - int rv, chan = pcm_data->rdma_ch;
> -
> - rv = regmap_read(drvdata->lpaif_map,
> - LPAIF_IRQSTAT_REG(v, LPAIF_IRQ_PORT_HOST), &interrupts);
> - if (rv) {
> - dev_err(soc_runtime->dev, "%s() error reading from irqstat reg: %d\n",
> - __func__, rv);
> - return IRQ_NONE;
> - }
> -
> - interrupts &= LPAIF_IRQ_ALL(chan);
> + int rv;
>
> if (interrupts & LPAIF_IRQ_PER(chan)) {
> rv = regmap_write(drvdata->lpaif_map,
> @@ -422,6 +410,30 @@ static irqreturn_t lpass_platform_lpaif_irq(int irq, void *data)
> return ret;

You are returning the ISR result here...

> }
>
> +static irqreturn_t lpass_platform_lpaif_irq(int irq, void *data)
> +{
> + struct lpass_data *drvdata = data;
> + struct lpass_variant *v = drvdata->variant;
> + unsigned int irqs;
> + int rv, chan;
> +
> + rv = regmap_read(drvdata->lpaif_map,
> + LPAIF_IRQSTAT_REG(v, LPAIF_IRQ_PORT_HOST), &irqs);
> + if (rv) {
> + pr_err("%s() error reading from irqstat reg: %d\n",
> + __func__, rv);
> + return IRQ_NONE;
> + }
> +
> + /* Handle per channel interrupts */
> + for (chan = 0; chan < LPASS_MAX_DMA_CHANNELS; chan++)
> + if (irqs & LPAIF_IRQ_ALL(chan) && drvdata->substream[chan])
> + lpass_dma_interrupt_handler(drvdata->substream[chan],
> + drvdata, chan, irqs);

...but ignoring the result here and always returning HANDLED.

> +
> + return IRQ_HANDLED;
> +}
> +

> int asoc_qcom_lpass_platform_register(struct platform_device *pdev)
> {
> struct lpass_data *drvdata = platform_get_drvdata(pdev);
> + struct lpass_variant *v = drvdata->variant;
> + int ret;
>
> drvdata->lpaif_irq = platform_get_irq_byname(pdev, "lpass-irq-lpaif");
> if (drvdata->lpaif_irq < 0) {
> @@ -553,6 +553,25 @@ int asoc_qcom_lpass_platform_register(struct platform_device *pdev)
> return -ENODEV;
> }
>
> + ret = devm_request_irq(&pdev->dev, drvdata->lpaif_irq,
> + lpass_platform_lpaif_irq, IRQF_TRIGGER_RISING,
> + "lpass-irq-lpaif", drvdata);
> + if (ret) {
> + dev_err(&pdev->dev, "%s() irq request failed: %d\n",
> + __func__, ret);
> + return ret;
> + }
> +
> + /* ensure audio hardware is disabled */
> + ret = regmap_write(drvdata->lpaif_map,
> + LPAIF_IRQEN_REG(v, LPAIF_IRQ_PORT_HOST), 0);
> + if (ret) {
> + dev_err(&pdev->dev, "%s() error writing to irqen reg: %d\n",
> + __func__, ret);
> + return ret;
> + }

Looking at this, it may be safer to disable the interrupt sources before
getting/enabling the interrupt, i.e. do the regmap_write first, then
devm_request_irq.

--
Kenneth Westfield
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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