[Intel-gfx] [PATCH] drm/i915: Sanitycheck PCI BARs on probe

[Piotr Piórkowski]

Jani Nikula <jani.nikula at linux.intel.com> wrote on pią [2022-maj-20 10:40:01 +0300]:
> On Thu, 20 Jan 2022, "Piorkowski, Piotr" <piotr.piorkowski at intel.com> wrote:
> > From: Piotr Piórkowski <piotr.piorkowski at intel.com>
> >
> > For proper operation of i915 we need usable PCI BARs:
> >  - GTTMMADDR BAR 0 (1 for GEN2)
> >  - GFXMEM BAR 2.
> > Lets check before we start the i915 probe that these BARs are set,
> > and that they have a size greater than 0.
> >
> > Signed-off-by: Piotr Piórkowski <piotr.piorkowski at intel.com>
> > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> > Cc: Jani Nikula <jani.nikula at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_pci.c         | 33 +++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_pci_config.h |  5 ++++
> >  2 files changed, 38 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
> > index 8261b6455747..ad60c69d9dd8 100644
> > --- a/drivers/gpu/drm/i915/i915_pci.c
> > +++ b/drivers/gpu/drm/i915/i915_pci.c
> > @@ -29,6 +29,8 @@
> >  #include "i915_drv.h"
> >  #include "i915_pci.h"
> >  
> 
> Superfluous blank line.
> 
> > +#include "intel_pci_config.h"
> 
> Please put the includes together and sort.
> 

ok

> > +
> >  #define PLATFORM(x) .platform = (x)
> >  #define GEN(x) \
> >  	.graphics.ver = (x), \
> > @@ -1181,6 +1183,34 @@ static bool force_probe(u16 device_id, const char *devices)
> >  	return ret;
> >  }
> >  
> > +static bool __pci_resource_valid(struct pci_dev *pdev, int bar)
> > +{
> > +	if (!pci_resource_flags(pdev, bar))
> > +		return false;
> > +
> > +	if (pci_resource_flags(pdev, bar) & IORESOURCE_UNSET)
> > +		return false;
> > +
> > +	if (!pci_resource_len(pdev, bar))
> > +		return false;
> > +
> > +	return true;
> > +}
> > +
> > +static bool intel_bars_valid(struct pci_dev *pdev, struct intel_device_info *intel_info)
> > +{
> > +	const int gttmmaddr_bar = intel_info->graphics.ver == 2 ? GEN2_GTTMMADR_BAR : GTTMMADR_BAR;
> > +	const int gfxmem_bar = GFXMEM_BAR;
> 
> We don't usually bother with const for non-pointer local variables.

ok
> 
> > +
> > +	if (!__pci_resource_valid(pdev, gttmmaddr_bar))
> > +		return false;
> > +
> > +	if (!__pci_resource_valid(pdev, gfxmem_bar))
> > +		return false;
> > +
> > +	return true;
> > +}
> > +
> >  static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> >  {
> >  	struct intel_device_info *intel_info =
> > @@ -1206,6 +1236,9 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> >  	if (PCI_FUNC(pdev->devfn))
> >  		return -ENODEV;
> >  
> > +	if (!intel_bars_valid(pdev, intel_info))
> > +		return -ENODEV;
> > +
> >  	/* Detect if we need to wait for other drivers early on */
> >  	if (intel_modeset_probe_defer(pdev))
> >  		return -EPROBE_DEFER;
> > diff --git a/drivers/gpu/drm/i915/intel_pci_config.h b/drivers/gpu/drm/i915/intel_pci_config.h
> > index 12cd9d4f23de..c08fd5d48ada 100644
> > --- a/drivers/gpu/drm/i915/intel_pci_config.h
> > +++ b/drivers/gpu/drm/i915/intel_pci_config.h
> > @@ -6,6 +6,11 @@
> >  #ifndef __INTEL_PCI_CONFIG_H__
> >  #define __INTEL_PCI_CONFIG_H__
> >  
> > +/* PCI BARs */
> > +#define GTTMMADR_BAR				0
> > +#define GEN2_GTTMMADR_BAR			1
> > +#define GFXMEM_BAR				2
> 
> Is anyone outside of intel_pci_config.c going to need these? They could
> be there if not.
> 
We could use this in all i915. There are lots of places where we use BAR numbers
instead of constants when operating on pci resources.
E.g. all intel_pci_resource calls, or directs calls pci_resource_start
and pci_resource_len.
For now, we use two ( and an exception for gen2) BARs in i915,
but there may be more in the future.
It may be useful to organize this.

Thanks for review!
Piotr

> BR,
> Jani.
> 
> 
> > +
> >  /* BSM in include/drm/i915_drm.h */
> >  
> >  #define MCHBAR_I915				0x44
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center

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