linux-kernel - Re: [PATCH v3] media: dvb: Provide 4 devm variants

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Date:   Mon, 22 Jul 2019 10:13:56 +0200
From:   Marc Gonzalez <marc.w.gonzalez@...e.fr>
To:     Ezequiel Garcia <ezequiel@...labora.com>,
        Sean Young <sean@...s.org>, Brad Love <brad@...tdimension.cc>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Jonathan Neuschäfer <j.neuschaefer@....net>
Cc:     linux-media <linux-media@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH v3] media: dvb: Provide 4 devm variants

On 21/07/2019 17:02, Ezequiel Garcia wrote:

> On Thu, 2019-07-18 at 15:03 +0200, Marc Gonzalez wrote:
>
>> Provide devm variants for automatic resource release on device removal.
>> Makes error-handling in probe() simpler, thus less error-prone.
>> Once all resources are devmanaged, remove() is no longer needed.
> 
> I think it would be better to add this API as part of a series
> that also uses it.

I have an outstanding RFC for a new driver:

	https://patchwork.kernel.org/patch/11040435/

Locally, I've updated the probe function to use the proposed devm functions.

I was mainly hoping to get initial feedback from the maintainers.
1) See if they're OK with devm APIs
2) See if they're OK with the way I implemented devm APIs
3) See what's missing to get an Ack

static int tsif_probe(struct platform_device *pdev)
{
	int err, virq;
	struct tsif *tsif;
	struct resource *res;
	struct dvb_frontend *fe;
	struct dvb_adapter *adap;
	struct device *dev = &pdev->dev;
	short num = DVB_UNSET;

	fe = dvb_get_demod_fe(dev->of_node);
	if (!fe)
		return -ENXIO;

	tsif = devm_kzalloc(dev, sizeof(*tsif), GFP_KERNEL);
	if (!tsif)
		return -ENOMEM;

	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "tsif0");
	tsif->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(tsif->base))
		return PTR_ERR(tsif->base);

	virq = platform_get_irq_byname(pdev, "tsif0");
	err = devm_request_irq(dev, virq, tsif_isr, IRQF_SHARED, "tsif", tsif);
	if (err)
		return err;

	tsif->clk = devm_clk_get(dev, "iface");
	if (IS_ERR(tsif->clk))
		return PTR_ERR(tsif->clk);

	err = devm_clk_prepare_enable(dev, tsif->clk);
	if (err)
		return err;

	adap = &tsif->adapter;
	err = devm_dvb_register_adapter(dev, adap, "tsif", THIS_MODULE, &num);
	if (err) return err;

	/* Not sure the diff between filter and feed? */
	tsif->demux.filternum = 16; /*** Dunno what to put here ***/
	tsif->demux.feednum = 16;	/*** Dunno what to put here ***/
	tsif->demux.start_feed = noop;
	tsif->demux.stop_feed = noop;
	err = devm_dvb_dmx_init(dev, &tsif->demux);
	if (err) return err;

	/* What relation to dvb_demux.filternum??? */
	/* Do I need this object?? */
	tsif->dmxdev.filternum = 16;
	tsif->dmxdev.demux = &tsif->demux.dmx;
	err = devm_dvb_dmxdev_init(dev, &tsif->dmxdev, adap);
	if (err) return err;

	err = devm_dvb_register_frontend(dev, adap, fe);
	if (err) return err;

	writel_relaxed(TSIF_START + ENABLE_IRQ, tsif->base + TSIF_STS_CTL);
	devm_add_action(dev, stop_tsif, tsif);
	INIT_WORK(&tsif->work, handle_pkt);

	return 0;
}