Not sure whether this is important, but in drivers/video/sis/init301.c:1557:
if((SiS_Pr->ChipType >= SIS_661) || (SiS_Pr->SiS_ROMNew)) {
SiS_Pr->SiS_LCDTypeInfo = (SiS_GetReg(SiS_Pr->SiS_P3d4,0x39) & 0x7c) >> 2;
} else if((SiS_Pr->ChipType < SIS_315H) || (SiS_Pr->ChipType >= SIS_661)) {
SiS_Pr->SiS_LCDTypeInfo = temp >> 4;
note the duplicate test for 'SiS_Pr->ChipType >= SIS_661'
if it was true in the first test, the second test won't be evaluated.