linux-kernel - Re: [Patch v4 03/10] memory: tegra: add interconnect support for DRAM scaling in Tegra234

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Message-ID: <ZCLJ895gHPXQE+Lz@orome>
Date:   Tue, 28 Mar 2023 13:05:23 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Sumit Gupta <sumitg@...dia.com>, treding@...dia.com,
        dmitry.osipenko@...labora.com, viresh.kumar@...aro.org,
        rafael@...nel.org, jonathanh@...dia.com, robh+dt@...nel.org,
        lpieralisi@...nel.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pci@...r.kernel.org,
        mmaddireddy@...dia.com, kw@...ux.com, bhelgaas@...gle.com,
        vidyas@...dia.com, sanjayc@...dia.com, ksitaraman@...dia.com,
        ishah@...dia.com, bbasu@...dia.com
Subject: Re: [Patch v4 03/10] memory: tegra: add interconnect support for
 DRAM scaling in Tegra234

On Tue, Mar 28, 2023 at 09:31:58AM +0200, Krzysztof Kozlowski wrote:
> On 27/03/2023 18:14, Sumit Gupta wrote:
[...]
> > diff --git a/drivers/memory/tegra/tegra186-emc.c b/drivers/memory/tegra/tegra186-emc.c
[...]
> > @@ -158,6 +260,9 @@ static int tegra186_emc_probe(struct platform_device *pdev)
> >  	if (!emc)
> >  		return -ENOMEM;
> >  
> > +	platform_set_drvdata(pdev, emc);
> > +	emc->dev = &pdev->dev;
> 
> This patch looks like stiched from two or more patches... emc->dev does
> not look like new member of emc, thus why do you set in exisitng
> function in this patch? Why it wasn't needed before?

This looks like it may be leftover from some development. These two
lines exist in this driver a few lines further down. Either one pair
should be removed. I don't see why this would need to be moved, so
probably the above additions can just be dropped.

Thierry

> >  	emc->bpmp = tegra_bpmp_get(&pdev->dev);
> >  	if (IS_ERR(emc->bpmp))
> >  		return dev_err_probe(&pdev->dev, PTR_ERR(emc->bpmp), "failed to get BPMP\n");
> > @@ -236,6 +341,25 @@ static int tegra186_emc_probe(struct platform_device *pdev)
> >  	debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
> >  			    emc, &tegra186_emc_debug_max_rate_fops);
> >  
> > +	mc = dev_get_drvdata(emc->dev->parent);
> > +	if (mc && mc->soc->icc_ops) {
> > +		/*
> > +		 * Initialize the ICC even if BPMP-FW doesn't support 'MRQ_BWMGR_INT'.
> > +		 * Use the flag 'mc->bwmgr_mrq_supported' within MC driver and return
> > +		 * EINVAL instead of passing the request to BPMP-FW later when the BW
> > +		 * request is made by client with 'icc_set_bw()' call.
> > +		 */
> > +		err = tegra_emc_interconnect_init(emc);
> > +		if (err)
> > +			goto put_bpmp;
> > +
> > +		if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT))
> > +			mc->bwmgr_mrq_supported = true;
> > +		else
> > +
> 
> Drop blank line.
> 
> > +			dev_info(&pdev->dev, "MRQ_BWMGR_INT not present\n");
> 
> And what user is supposed to do with this? Either make it descriptive or
> drop.

Agreed. I think we can just drop this. If the intention was to provide a
quick way for people to detect whether BWMGR is available or not, using
something from sysfs/debugfs would be preferable.

Thierry

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