On Mon, 23 Sep 2024, Ville Syrjälä <[email protected]> wrote: > On Mon, Sep 23, 2024 at 12:12:39PM +0300, Jani Nikula wrote: >> On Fri, 20 Sep 2024, Ville Syrjälä <[email protected]> wrote: >> > On Thu, Sep 12, 2024 at 03:15:52PM +0300, Jani Nikula wrote: >> >> On Tue, 10 Sep 2024, Ville Syrjala <[email protected]> wrote: >> >> > From: Ville Syrjälä <[email protected]> >> >> > >> >> > Replace the three hand rolled "$VBT"s with a vbt_signature[] >> >> > to avoid accidents. >> >> > >> >> > Signed-off-by: Ville Syrjälä <[email protected]> >> >> > --- >> >> > drivers/gpu/drm/i915/display/intel_bios.c | 12 +++++++++--- >> >> > 1 file changed, 9 insertions(+), 3 deletions(-) >> >> > >> >> > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c >> >> > b/drivers/gpu/drm/i915/display/intel_bios.c >> >> > index cbbda94c3dab..0b92b494117f 100644 >> >> > --- a/drivers/gpu/drm/i915/display/intel_bios.c >> >> > +++ b/drivers/gpu/drm/i915/display/intel_bios.c >> >> > @@ -2964,6 +2964,8 @@ static const struct bdb_header >> >> > *get_bdb_header(const struct vbt_header *vbt) >> >> > return _vbt + vbt->bdb_offset; >> >> > } >> >> > >> >> > +static const char vbt_signature[4] = "$VBT"; >> >> >> >> Always a bit scary to add strings without termination, but I guess it's >> >> justified here. >> > >> > I guess we could make it look less like a string with eg. >> > static const u8 vbt_signature[] = { '$', 'V', 'B', 'T' }; >> > ? >> >> Alternatively, >> >> static const char *vbt_signature = "$VBT"; > > Or could just be something like: > > static const char vbt_signature[] = "$VBT"; > static const int vbt_signature_len = 4; > > BUILD_BUG_ON(vbt_signature_len != sizeof(vbt_signature) - 1); > BUILD_BUG_ON(vbt_signature_len != sizeof(u32)); > > and use vbt_signature_len instead sizeof(vbt_signature) everwhere.
Works for me, up to you. BR, Jani. > >> >> > >> >> Reviewed-by: Jani Nikula <[email protected]> >> >> >> >> >> >> > + >> >> > /** >> >> > * intel_bios_is_valid_vbt - does the given buffer contain a valid VBT >> >> > * @display: display device >> >> > @@ -2986,7 +2988,7 @@ bool intel_bios_is_valid_vbt(struct intel_display >> >> > *display, >> >> > return false; >> >> > } >> >> > >> >> > - if (memcmp(vbt->signature, "$VBT", 4)) { >> >> > + if (memcmp(vbt->signature, vbt_signature, >> >> > sizeof(vbt_signature))) { >> >> But then this would need strlen() >> >> >> > drm_dbg_kms(display->drm, "VBT invalid signature\n"); >> >> > return false; >> >> > } >> >> > @@ -3082,9 +3084,11 @@ static struct vbt_header >> >> > *spi_oprom_get_vbt(struct intel_display *display, >> >> > oprom_offset = intel_uncore_read(&i915->uncore, OROM_OFFSET); >> >> > oprom_offset &= OROM_OFFSET_MASK; >> >> > >> >> > + BUILD_BUG_ON(sizeof(vbt_signature) != sizeof(u32)); >> >> And maybe this could be sizeof(vbt_signature) < sizeof(u32) >> >> All of the alternatives are a bit disappointing, so maybe let's just >> roll with the patch you already have here? >> >> BR, >> Jani. >> >> >> > + >> >> > for (count = 0; count < oprom_size; count += 4) { >> >> > data = intel_spi_read32(&i915->uncore, oprom_offset + >> >> > count); >> >> > - if (data == *((const u32 *)"$VBT")) { >> >> > + if (data == *((const u32 *)vbt_signature)) { >> >> > found = oprom_offset + count; >> >> > break; >> >> > } >> >> > @@ -3144,9 +3148,11 @@ static struct vbt_header *oprom_get_vbt(struct >> >> > intel_display *display, >> >> > if (!oprom) >> >> > return NULL; >> >> > >> >> > + BUILD_BUG_ON(sizeof(vbt_signature) != sizeof(u32)); >> >> > + >> >> > /* Scour memory looking for the VBT signature. */ >> >> > for (i = 0; i + 4 < size; i += 4) { >> >> > - if (ioread32(oprom + i) != *((const u32 *)"$VBT")) >> >> > + if (ioread32(oprom + i) != *((const u32 >> >> > *)vbt_signature)) >> >> > continue; >> >> > >> >> > p = oprom + i; >> >> >> >> -- >> >> Jani Nikula, Intel >> >> -- >> Jani Nikula, Intel -- Jani Nikula, Intel
