On Wed, May 13, 2015 at 03:34:05PM +0300, Jani Nikula wrote:
> Add one explicit discard of __iomem address space qualifier in
> validate_vbt(), and respect it otherwise. This adds clarity in the code,
> and reduces the sparse warnings from the module to just one.
>
> Quoting Daniel, "The vbt really is plain old memory. Except that it's
> reserved in the e820 table as something special and hence treated as io
> range by the kernel. But it is memory, hence casting away the __iomem is
> imo the right approach."
>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Merged entire series, thanks.
-Daniel
> ---
> drivers/gpu/drm/i915/intel_bios.c | 21 ++++++++++++++-------
> 1 file changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index 6e018ba53035..198fc3c3291b 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -1199,15 +1199,22 @@ static const struct dmi_system_id intel_no_opregion_vbt[] = {
> { }
> };
>
> -static const struct bdb_header *validate_vbt(const void *base, size_t size,
> - const void *_vbt,
> +static const struct bdb_header *validate_vbt(const void __iomem *_base,
> + size_t size,
> + const void __iomem *_vbt,
> const char *source)
> {
> - const struct vbt_header *vbt = _vbt;
> - size_t offset;
> + /*
> + * This is the one place where we explicitly discard the address space
> + * (__iomem) of the BIOS/VBT. (And this will cause a sparse complaint.)
> + * From now on everything is based on 'base', and treated as regular
> + * memory.
> + */
> + const void *base = (const void *) _base;
> + size_t offset = _vbt - _base;
> + const struct vbt_header *vbt = base + offset;
> const struct bdb_header *bdb;
>
> - offset = _vbt - base;
> if (offset + sizeof(struct vbt_header) > size) {
> DRM_DEBUG_DRIVER("VBT header incomplete\n");
> return NULL;
> @@ -1235,14 +1242,14 @@ static const struct bdb_header *validate_vbt(const void *base, size_t size,
> return bdb;
> }
>
> -static const struct bdb_header *find_vbt(void *bios, size_t size)
> +static const struct bdb_header *find_vbt(void __iomem *bios, size_t size)
> {
> const struct bdb_header *bdb = NULL;
> size_t i;
>
> /* Scour memory looking for the VBT signature. */
> for (i = 0; i + 4 < size; i++) {
> - if (memcmp(bios + i, "$VBT", 4) == 0) {
> + if (ioread32(bios + i) == *((const u32 *) "$VBT")) {
> bdb = validate_vbt(bios, size, bios + i, "PCI ROM");
> break;
> }
> --
> 2.1.4
>
> _______________________________________________
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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