Dear coreboot folks,
Am Donnerstag, den 18.04.2013, 19:58 +0200 schrieb Stefan Tauner:
andor reported a problem where flashrom does
reproducibly not work with
coreboot but does with the vendor BIOS
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
static void enable_spi_fast_mode(void)
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;
spi_base = (byte & ~(3 << 14)) | (1 << 14);
spi_base = spi_base | (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?
MacGyver reported the same problems with the MXIC MX25L3206EPI in
#coreboot on <irc.freenode.net>. In the end after several hours, Kyösti
was the one remembering the problem reported by Stefan – though Andor
had it with a W25Q64 chip – and Kyösti even submitted a patch to Gerrit
. Unfortunately MacGyver reports that it does not fix his problem
yet, although the NormSpeed problem seems fixed.
PS: No idea, if the flashrom mailing list should be put in CC.