Skip to content
Permalink
Browse files

[realtek] Ensure EEPROM writes reach chip before starting udelay()

On some systems, it appears to be possible for writes to the EEPROM
registers to be delayed for long enough that the EEPROM's setup and
hold times are violated, resulting in invalid data being read from the
EEPROM.

Fix by inserting a PCI read cycle immediately after writes to
RTL_9346CR, to ensure that the write has completed before starting the
udelay() used to time the SPI bus transitions.

Reported-by: Gelip <mrgelip@gmail.com>
Tested-by: Gelip <mrgelip@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
  • Loading branch information
mcb30 committed May 1, 2013
1 parent c6375a8 commit 9b1ec3132fed94c644c77a5e59a8ba2112110455
Showing with 3 additions and 0 deletions.
  1. +3 −0 src/drivers/net/realtek.c
@@ -74,6 +74,7 @@ static void realtek_spi_open_bit ( struct bit_basher *basher ) {

/* Enable EEPROM access */
writeb ( RTL_9346CR_EEM_EEPROM, rtl->regs + RTL_9346CR );
readb ( rtl->regs + RTL_9346CR ); /* Ensure write reaches chip */
}

/**
@@ -87,6 +88,7 @@ static void realtek_spi_close_bit ( struct bit_basher *basher ) {

/* Disable EEPROM access */
writeb ( RTL_9346CR_EEM_NORMAL, rtl->regs + RTL_9346CR );
readb ( rtl->regs + RTL_9346CR ); /* Ensure write reaches chip */
}

/**
@@ -129,6 +131,7 @@ static void realtek_spi_write_bit ( struct bit_basher *basher,
reg &= ~mask;
reg |= ( data & mask );
writeb ( reg, rtl->regs + RTL_9346CR );
readb ( rtl->regs + RTL_9346CR ); /* Ensure write reaches chip */
DBG_ENABLE ( DBGLVL_IO );
}

0 comments on commit 9b1ec31

Please sign in to comment.