Subject: [PATCH 2/2] mmc: atmel-mci: introduce probe deferring

From: [email-masked] (Nicolas Ferre)
Date: Fri, 14 Nov 2014 15:53:10 +0100

On 14/11/2014 15:33, Ludovic Desroches :
> Return probe defer if requesting a dma channel without a dma controller
> probed. Using late_initcall is no more needing.
> 
> Signed-off-by: Ludovic Desroches <[email-masked]>
> ---
>  drivers/mmc/host/atmel-mci.c | 52 +++++++++++++++++++++++++-------------------
>  1 file changed, 30 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
> index de2287c..caddbbd 100644
> --- a/drivers/mmc/host/atmel-mci.c
> +++ b/drivers/mmc/host/atmel-mci.c
> @@ -2272,37 +2272,40 @@ static void atmci_cleanup_slot(struct atmel_mci_slot *slot,
>  	mmc_free_host(slot->mmc);
>  }
>  
> -static bool atmci_configure_dma(struct atmel_mci *host)
> +static int atmci_configure_dma(struct atmel_mci *host)
>  {
>  	struct mci_platform_data	*pdata;
>  	dma_cap_mask_t mask;
> +	int ret = 0;
>  
>  	if (host == NULL)
> -		return false;
> +		return -EINVAL;
>  
>  	pdata = host->pdev->dev.platform_data;
>  
>  	dma_cap_zero(mask);
>  	dma_cap_set(DMA_SLAVE, mask);
>  
> -	host->dma.chan = dma_request_slave_channel(&host->pdev->dev, "rxtx");
> -	if (!host->dma.chan) {
> -		dev_warn(&host->pdev->dev, "no DMA channel available\n");
> -		return false;
> -	} else {
> -		dev_info(&host->pdev->dev,
> -					"using %s for DMA transfers\n",
> -					dma_chan_name(host->dma.chan));
> -
> -		host->dma_conf.src_addr = host->mapbase + ATMCI_RDR;
> -		host->dma_conf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> -		host->dma_conf.src_maxburst = 1;
> -		host->dma_conf.dst_addr = host->mapbase + ATMCI_TDR;
> -		host->dma_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> -		host->dma_conf.dst_maxburst = 1;
> -		host->dma_conf.device_fc = false;
> -		return true;
> +	host->dma.chan = dma_request_slave_channel_reason(&host->pdev->dev, "rxtx");
> +	if (IS_ERR(host->dma.chan)) {
> +		ret = PTR_ERR(host->dma.chan);
> +		if (ret != -EPROBE_DEFER)
> +			dev_warn(&host->pdev->dev, "no DMA channel available\n");
> +		return ret;
>  	}
> +
> +	dev_info(&host->pdev->dev,
> +			"using %s for DMA transfers\n",
> +			dma_chan_name(host->dma.chan));
> +
> +	host->dma_conf.src_addr = host->mapbase + ATMCI_RDR;
> +	host->dma_conf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> +	host->dma_conf.src_maxburst = 1;
> +	host->dma_conf.dst_addr = host->mapbase + ATMCI_TDR;
> +	host->dma_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> +	host->dma_conf.dst_maxburst = 1;
> +	host->dma_conf.device_fc = false;
> +	return ret;
>  }
>  
>  /*
> @@ -2419,7 +2422,10 @@ static int __init atmci_probe(struct platform_device *pdev)
>  
>  	/* Get MCI capabilities and set operations according to it */
>  	atmci_get_cap(host);
> -	if (atmci_configure_dma(host)) {
> +	ret = atmci_configure_dma(host);
> +	if (ret == -EPROBE_DEFER)
> +		goto err_dma_probe_defer;
> +	if (ret == 0) {
>  		host->prepare_data = &atmci_prepare_data_dma;
>  		host->submit_data = &atmci_submit_data_dma;
>  		host->stop_transfer = &atmci_stop_transfer_dma;
> @@ -2506,6 +2512,7 @@ err_init_slot:
>  	del_timer_sync(&host->timer);
>  	if (host->dma.chan)
>  		dma_release_channel(host->dma.chan);
> +err_dma_probe_defer:
>  	free_irq(irq, host);
>  	return ret;
>  }
> @@ -2573,6 +2580,7 @@ static const struct dev_pm_ops atmci_dev_pm_ops = {
>  };
>  
>  static struct platform_driver atmci_driver = {
> +	.probe		= atmci_probe,
>  	.remove		= __exit_p(atmci_remove),
>  	.driver		= {
>  		.name		= "atmel_mci",
> @@ -2583,7 +2591,7 @@ static struct platform_driver atmci_driver = {
>  
>  static int __init atmci_init(void)
>  {
> -	return platform_driver_probe(&atmci_driver, atmci_probe);
> +	return platform_driver_register(&atmci_driver);
>  }
>  
>  static void __exit atmci_exit(void)
> @@ -2591,7 +2599,7 @@ static void __exit atmci_exit(void)
>  	platform_driver_unregister(&atmci_driver);
>  }
>  
> -late_initcall(atmci_init); /* try to load after dma driver when built-in */
> +subsys_initcall(atmci_init);

If deferring probe is activated, so I don't know why a special initcall
function is still needed.

>  module_exit(atmci_exit);
>  
>  MODULE_DESCRIPTION("Atmel Multimedia Card Interface driver");
> 

-- 
Nicolas Ferre