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SubjectRe: [PATCH] mmc: omap: Use dma_request_chan() for requesting DMA channel
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On 4 May 2016 at 05:59, Peter Ujfalusi <peter.ujfalusi@ti.com> wrote:
> On 05/03/2016 11:00 PM, Peter Ujfalusi wrote:
>>>> @@ -1382,29 +1379,31 @@ static int mmc_omap_probe(struct platform_device *pdev)
>>>> goto err_free_iclk;
>>>> }
>>>>
>>>> - dma_cap_zero(mask);
>>>> - dma_cap_set(DMA_SLAVE, mask);
>>>> -
>>>> host->dma_tx_burst = -1;
>>>> host->dma_rx_burst = -1;
>>>>
>>>> - res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "tx");
>>>> - if (res)
>>>> - sig = res->start;
>>>> - host->dma_tx = dma_request_slave_channel_compat(mask,
>>>> - omap_dma_filter_fn, &sig, &pdev->dev, "tx");
>>>> - if (!host->dma_tx)
>>>> - dev_warn(host->dev, "unable to obtain TX DMA engine channel %u\n",
>>>> - sig);
>>>> -
>>>> - res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "rx");
>>>> - if (res)
>>>> - sig = res->start;
>>>> - host->dma_rx = dma_request_slave_channel_compat(mask,
>>>> - omap_dma_filter_fn, &sig, &pdev->dev, "rx");
>>>> - if (!host->dma_rx)
>>>> - dev_warn(host->dev, "unable to obtain RX DMA engine channel %u\n",
>>>> - sig);
>>>> + host->dma_tx = dma_request_chan(&pdev->dev, "tx");
>>>> + if (IS_ERR(host->dma_tx)) {
>>>> + ret = PTR_ERR(host->dma_tx);
>>>> + if (ret == -EPROBE_DEFER)
>>>> + goto err_free_iclk;
>>
>> and one clk_put(host->fclk) is missing from here.
>>
>>>> +
>>>> + host->dma_tx = NULL;
>>>
>>> Instead of setting this to NULL, let's keep its value and later check
>>> it with IS_ERR() when needed.
>>
>> I thought about it, but decided against without need to have changes in other
>> places in the driver.
>
> This sentence does not make too much sense ;) Let's try it again:
> So, I have considered to use PTR_ERR in the driver for the DMA channel, but I
> wanted to avoid too broad changes in the driver. Keeping the ERR_PTR would
> bring no runtime benefit since we only care if we have channel or not.

Okay, so let's deal with that separately instead then.

Kind regards
Uffe

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