linux-kernel - Re: [PATCH v2 4/5] mmc: davinci: don't use dma platform resources

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Message-ID: <56E7CE21.7070605@ti.com>
Date:	Tue, 15 Mar 2016 10:56:01 +0200
From:	Peter Ujfalusi <peter.ujfalusi@...com>
To:	David Lechner <david@...hnology.com>, <nsekhar@...com>
CC:	<ulf.hansson@...aro.org>, <khilman@...nel.org>,
	<linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 4/5] mmc: davinci: don't use dma platform resources

On 03/15/16 10:54, Peter Ujfalusi wrote:
> On 03/15/16 00:54, David Lechner wrote:
>> The davinci arch now has dma_slave_map tables for dma resources, so it is
>> no longer necessary to pass dma resources through the platform device.
>>
>> Signed-off-by: David Lechner <david@...hnology.com>
>> ---
>>
>> v2 changes: Remove platform_get_resource completly instead of just ignoring it.
>>
>>
>>  drivers/mmc/host/davinci_mmc.c | 19 ++-----------------
>>  1 file changed, 2 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
>> index 8d10a92..dc96401 100644
>> --- a/drivers/mmc/host/davinci_mmc.c
>> +++ b/drivers/mmc/host/davinci_mmc.c
>> @@ -202,7 +202,6 @@ struct mmc_davinci_host {
>>  	u32 buffer_bytes_left;
>>  	u32 bytes_left;
>>  
>> -	u32 rxdma, txdma;
>>  	struct dma_chan *dma_tx;
>>  	struct dma_chan *dma_rx;
>>  	bool use_dma;
>> @@ -520,16 +519,14 @@ static int __init davinci_acquire_dma_channels(struct mmc_davinci_host *host)
>>  	dma_cap_set(DMA_SLAVE, mask);
>>  
>>  	host->dma_tx =
>> -		dma_request_slave_channel_compat(mask, edma_filter_fn,
>> -				&host->txdma, mmc_dev(host->mmc), "tx");
>> +		dma_request_slave_channel(mmc_dev(host->mmc), "tx");
> 
> you would need to use dma_request_chan() to be able to rely on the legacy
> channel mapping.

In other words: w/o dma_request_chan() legacy boot will not work as you will
not get the DMA channel.

> I have staged commits for converting all daVinci and OMAP drivers, I'll attach
> the patch I have for davinci-mmc for reference.
> When we convert to use the dma_request_chan() we can handle deferred probing
> also...
> 
> 
> 
>>  	if (!host->dma_tx) {
>>  		dev_err(mmc_dev(host->mmc), "Can't get dma_tx channel\n");
>>  		return -ENODEV;
>>  	}
>>  
>>  	host->dma_rx =
>> -		dma_request_slave_channel_compat(mask, edma_filter_fn,
>> -				&host->rxdma, mmc_dev(host->mmc), "rx");
>> +		dma_request_slave_channel(mmc_dev(host->mmc), "rx");
>>  	if (!host->dma_rx) {
>>  		dev_err(mmc_dev(host->mmc), "Can't get dma_rx channel\n");
>>  		r = -ENODEV;
>> @@ -1251,18 +1248,6 @@ static int __init davinci_mmcsd_probe(struct platform_device *pdev)
>>  	host = mmc_priv(mmc);
>>  	host->mmc = mmc;	/* Important */
>>  
>> -	r = platform_get_resource(pdev, IORESOURCE_DMA, 0);
>> -	if (!r)
>> -		dev_warn(&pdev->dev, "RX DMA resource not specified\n");
>> -	else
>> -		host->rxdma = r->start;
>> -
>> -	r = platform_get_resource(pdev, IORESOURCE_DMA, 1);
>> -	if (!r)
>> -		dev_warn(&pdev->dev, "TX DMA resource not specified\n");
>> -	else
>> -		host->txdma = r->start;
>> -
>>  	host->mem_res = mem;
>>  	host->base = devm_ioremap(&pdev->dev, mem->start, mem_size);
>>  	if (!host->base)
>>
> 
> 


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