linux-kernel - Re: [PATCH v10 06/10] drm/i915/nvm: add nvm device for discrete graphics

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Message-ID: <aDGdWof1HfViERND@black.fi.intel.com>
Date: Sat, 24 May 2025 13:20:10 +0300
From: Raag Jadav <raag.jadav@...el.com>
To: Alexander Usyskin <alexander.usyskin@...el.com>
Cc: Miquel Raynal <miquel.raynal@...tlin.com>,
	Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	Karthik Poosa <karthik.poosa@...el.com>,
	Reuven Abliyev <reuven.abliyev@...el.com>,
	Oren Weil <oren.jer.weil@...el.com>, linux-mtd@...ts.infradead.org,
	intel-xe@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Tomas Winkler <tomasw@...il.com>
Subject: Re: [PATCH v10 06/10] drm/i915/nvm: add nvm device for discrete
 graphics

On Thu, May 15, 2025 at 04:33:41PM +0300, Alexander Usyskin wrote:
> Enable access to internal non-volatile memory on
> DGFX devices via a child device.
> The nvm child device is exposed via auxiliary bus.

...

> +void intel_nvm_init(struct drm_i915_private *i915)
> +{

Lucas recently revamped xe driver to address this, so let's not hide bugs
and return an error where possible.

> +	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
> +	struct intel_dg_nvm_dev *nvm;
> +	struct auxiliary_device *aux_dev;
> +	int ret;
> +
> +	/* Only the DGFX devices have internal NVM */
> +	if (!IS_DGFX(i915))
> +		return;
> +
> +	/* Nvm pointer should be NULL here */
> +	if (WARN_ON(i915->nvm))
> +		return;
> +
> +	i915->nvm = kzalloc(sizeof(*nvm), GFP_KERNEL);
> +	if (!i915->nvm)
> +		return;
> +
> +	nvm = i915->nvm;
> +
> +	nvm->writeable_override = true;
> +	nvm->bar.parent = &pdev->resource[0];
> +	nvm->bar.start = GEN12_GUNIT_NVM_BASE + pdev->resource[0].start;
> +	nvm->bar.end = nvm->bar.start + GEN12_GUNIT_NVM_SIZE - 1;
> +	nvm->bar.flags = IORESOURCE_MEM;
> +	nvm->bar.desc = IORES_DESC_NONE;
> +	nvm->regions = regions;
> +
> +	aux_dev = &nvm->aux_dev;
> +
> +	aux_dev->name = "nvm";
> +	aux_dev->id = (pci_domain_nr(pdev->bus) << 16) |
> +		       PCI_DEVID(pdev->bus->number, pdev->devfn);

Why not just pci_dev_id()?

> +	aux_dev->dev.parent = &pdev->dev;
> +	aux_dev->dev.release = i915_nvm_release_dev;
> +
> +	ret = auxiliary_device_init(aux_dev);
> +	if (ret) {
> +		drm_err(&i915->drm, "i915-nvm aux init failed %d\n", ret);
> +		return;
> +	}
> +
> +	ret = auxiliary_device_add(aux_dev);
> +	if (ret) {
> +		drm_err(&i915->drm, "i915-nvm aux add failed %d\n", ret);
> +		auxiliary_device_uninit(aux_dev);
> +		return;
> +	}
> +}

Raag