On Tue, 10 Sep 2024, Ville Syrjala <[email protected]> wrote: > From: Ville Syrjälä <[email protected]> > > The SPI VBT codepath only knows how to read 4 bytes at a time. > So to read the 2 byte vbt_size it masks out the unwanted msbs. > Hide that little implementation detail inside a new intel_spi_read16() > helper. Alse rename the existing intel_spi_read() to intel_spi_read32() > to make it clear what it does. > > Signed-off-by: Ville Syrjälä <[email protected]> > --- > drivers/gpu/drm/i915/display/intel_bios.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c > b/drivers/gpu/drm/i915/display/intel_bios.c > index cc4a4cc2bf3e..cbbda94c3dab 100644 > --- a/drivers/gpu/drm/i915/display/intel_bios.c > +++ b/drivers/gpu/drm/i915/display/intel_bios.c > @@ -3053,13 +3053,18 @@ static struct vbt_header *firmware_get_vbt(struct > intel_display *display, > return vbt; > } > > -static u32 intel_spi_read(struct intel_uncore *uncore, u32 offset) > +static u32 intel_spi_read32(struct intel_uncore *uncore, u32 offset) > { > intel_uncore_write(uncore, PRIMARY_SPI_ADDRESS, offset); > > return intel_uncore_read(uncore, PRIMARY_SPI_TRIGGER); > } > > +static u16 intel_spi_read16(struct intel_uncore *uncore, u32 offset) > +{ > + return intel_spi_read32(uncore, offset) & 0xffff; > +} > + > static struct vbt_header *spi_oprom_get_vbt(struct intel_display *display, > size_t *size) > { > @@ -3078,7 +3083,7 @@ static struct vbt_header *spi_oprom_get_vbt(struct > intel_display *display, > oprom_offset &= OROM_OFFSET_MASK; > > for (count = 0; count < oprom_size; count += 4) { > - data = intel_spi_read(&i915->uncore, oprom_offset + count); > + data = intel_spi_read32(&i915->uncore, oprom_offset + count); > if (data == *((const u32 *)"$VBT")) { > found = oprom_offset + count; > break; > @@ -3094,9 +3099,8 @@ static struct vbt_header *spi_oprom_get_vbt(struct > intel_display *display, > } > > /* Get VBT size and allocate space for the VBT */ > - vbt_size = intel_spi_read(&i915->uncore, > - found + offsetof(struct vbt_header, > vbt_size)); > - vbt_size &= 0xffff; > + vbt_size = intel_spi_read16(&i915->uncore, > + found + offsetof(struct vbt_header, > vbt_size));
Pedantically if vbt_size was the last member of struct vbt_header this could read past the checked size, but it's not and meh. Also nothing to do with this change, apart from this hiding the detail. Still meh. Reviewed-by: Jani Nikula <[email protected]> > > if (vbt_size > oprom_size - count) { > drm_dbg(display->drm, > @@ -3109,7 +3113,7 @@ static struct vbt_header *spi_oprom_get_vbt(struct > intel_display *display, > goto err_not_found; > > for (count = 0; count < vbt_size; count += 4) > - *(vbt + store++) = intel_spi_read(&i915->uncore, found + count); > + *(vbt + store++) = intel_spi_read32(&i915->uncore, found + > count); > > if (!intel_bios_is_valid_vbt(display, vbt, vbt_size)) > goto err_free_vbt; -- Jani Nikula, Intel
