Hi,
andor reported a problem where flashrom does reproducibly not work with coreboot but does with the vendor BIOS http://paste.flashrom.org/view.php?id=1614
Apparently it is related to fast reads and/or the frequency. We have forced the fastReadEnable bit in the SPI_Cntrl0 from 1 to 0 and also set NormSpeed in SPI_Cntrl1 to 16.5 Mhz (previously was 0 i.e. 66 MHz) in flashrom and the problem vanished.
Coreboot hard codes the fast read setting in src/southbridge/amd/cimx/sb800/bootblock.c:
static void enable_spi_fast_mode(void) { u8 byte; u32 dword; device_t dev = PCI_DEV(0, 0x14, 0x03);
// set temp MMIO base volatile u32 *spi_base = (void *)0xa0000000; u32 save = pci_io_read_config32(dev, 0xa0); pci_io_write_config32(dev, 0xa0, (u32) spi_base | 2);
// early enable of SPI 33 MHz fast mode read byte = spi_base[3]; spi_base[3] = (byte & ~(3 << 14)) | (1 << 14); spi_base[0] = spi_base[0] | (1 << 18); // fast read enable
pci_io_write_config32(dev, 0xa0, save); }
Marc suggested that this should be configurable in the devicetree or by a kconfig setting. Also, the statements using "byte" do not make a lot of sense to me. Shouldn't that be a u32 instead?
The public documentation of the fastReadEnable is lacking any detail and I don't have access to the NDAed version of the RRG. Is my theory correct that the controller uses the 0x0B opcode with a fixed frequency (33 MHz?) instead of 0x03 with the frequency set by NormSpeed?