linux-kernel - Re: [PATCH v1 11/30] drm/tegra: dc: Support OPP and SoC core voltage scaling

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Message-ID: <6bbec0aa-732a-2feb-684a-b1d8cc6a0471@gmail.com>
Date:   Wed, 11 Nov 2020 00:17:30 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        Alan Stern <stern@...land.harvard.edu>,
        Peter Chen <Peter.Chen@....com>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Lee Jones <lee.jones@...aro.org>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        linux-samsung-soc@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-usb@...r.kernel.org, linux-pwm@...r.kernel.org,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH v1 11/30] drm/tegra: dc: Support OPP and SoC core voltage
 scaling

10.11.2020 23:29, Thierry Reding пишет:
>> +
>> +	dc->opp_table = dev_pm_opp_get_opp_table(dc->dev);
>> +	if (IS_ERR(dc->opp_table))
>> +		return dev_err_probe(dc->dev, PTR_ERR(dc->opp_table),
>> +				     "failed to prepare OPP table\n");
>> +
>> +	if (of_machine_is_compatible("nvidia,tegra20"))
>> +		hw_version = BIT(tegra_sku_info.soc_process_id);
>> +	else
>> +		hw_version = BIT(tegra_sku_info.soc_speedo_id);
>> +
>> +	hw_opp_table = dev_pm_opp_set_supported_hw(dc->dev, &hw_version, 1);
>> +	err = PTR_ERR_OR_ZERO(hw_opp_table);
> What's the point of this? A more canonical version would be:
> 
> 	if (IS_ERR(hw_opp_table)) {
> 		err = PTR_ERR(hw_opp_table);
> 		dev_err(dc->dev, ...);
> 		goto put_table;
> 	}
> 
> That uses the same number of lines but is much easier to read, in my
> opinion, because it is the canonical form.
> 

Your variant is much more difficult to read for me :/

I guess the only reason it could be "canonical" is because
PTR_ERR_OR_ZERO was added not so long time ago.

But don't worry, this code will be moved out in a v2 and it won't use
PTR_ERR_OR_ZERO.