linux-kernel - Re: [PATCH V14 3/5] i2c: tegra: Add DMA support

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Message-ID: <67f10b9a-9dbc-aa01-e83e-e5de440f23c6@gmail.com>
Date:   Thu, 7 Feb 2019 18:56:12 +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 V14 3/5] i2c: tegra: Add DMA support

07.02.2019 18:17, Sowjanya Komatineni пишет:
>>>
>>>> @@ -1124,6 +1453,10 @@ static int tegra_i2c_probe(struct platform_device *pdev)
>>>>  		}
>>>>  	}
>>>>  
>>>> +	ret = tegra_i2c_init_dma(i2c_dev);
>>>> +	if (ret < 0)
>>>> +		goto disable_div_clk;
>>>> +
>>>>  	ret = tegra_i2c_init(i2c_dev);
>>>>  	if (ret) {
>>>>  		dev_err(&pdev->dev, "Failed to initialize i2c controller\n");
>>>
>>>
>>> Missing DMA resourcing release on probe failure.
>>
> If probe fails due to other reasons, then I2C interface will not be available and boot will not even happen.
> Do we need DMA resourcing release?
> Probe can fail due to timeout or from pm_runtime.. and if i2c fails lots of things don’t happen properly and doesn’t boot.
> 
> Will add but want to check..
> 

1) There is no guarantee that other error cases won't return -EPROBE_DEFER.

2) I2C driver could be compiled as a module.

3) It is simply a bad programming practice to leak resources.