linux-kernel - Re: [PATCH V9 3/5] i2c: tegra: Add DMA support

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Message-ID: <6150de70-6ca8-944a-780a-4574ff2b21c7@gmail.com>
Date:   Fri, 1 Feb 2019 22:22:25 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Mantravadi Karthik <mkarthik@...dia.com>,
        Shardar Mohammed <smohammed@...dia.com>,
        Timo Alho <talho@...dia.com>
Cc:     "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Subject: Re: [PATCH V9 3/5] i2c: tegra: Add DMA support

01.02.2019 22:20, Sowjanya Komatineni пишет:
> 
>>> +static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev) {
>>> +	struct dma_chan *dma_chan;
>>> +	u32 *dma_buf;
>>> +	dma_addr_t dma_phys;
>>> +	int err = 0;
>>> +
>>> +	if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA))
>>> +		return -ENODEV;
>>
>> Driver shall not fail to probe if DMA driver is disabled, but to continue with the PIO-only mode available.
>>
>> Should be:
>>
>> 	if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA))
>> 		return 0;
>>
> Except EPROBE_DEFER, anything else returned from tegra_i2c_init_dma (ENODEV/ENOMEM) is ignored in i2c_probe
> DMA mode decision is based on xfer size and availability of dma channel or can be changed based on valid dma buf to shorten the line.
> 

Ah, sorry. I missed that, seems good then.