diff --git a/doc/release_notes/devel.rst b/doc/release_notes/devel.rst
index 3bd25de7a..44490b183 100644
--- a/doc/release_notes/devel.rst
+++ b/doc/release_notes/devel.rst
@@ -7,13 +7,12 @@ the next release of flashrom and which are currently only available by source
 code checkout (see :doc:`../dev_guide/building_from_source`). These changes
 may be further revised before the next release.
 
-Known issues
-============
+Bugs fixed
+==========
 
-AMD-based PCs with FCH are unable to read flash contents for internal (BIOS
-flash) chips larger than 16 MB, and attempting to do so may crash the system.
-Systems with AMD "Promontory" IO extenders (mostly "Zen" desktop platforms) are
-not currently supported.
+AMD-based PCs with FCH were unable to read flash contents for internal (BIOS
+flash) chips larger than 16 MB, and attempting to do so could crash the
+system.
 
 https://ticket.coreboot.org/issues/370
 
diff --git a/sb600spi.c b/sb600spi.c
index 4947447c0..f48e166cc 100644
--- a/sb600spi.c
+++ b/sb600spi.c
@@ -575,6 +575,11 @@ static int promontory_read_memmapped(struct flashctx *flash, uint8_t *buf,
 		unsigned int start, unsigned int len)
 {
 	struct sb600spi_data * data = (struct sb600spi_data *)flash->mst->spi.data;
+
+	/* If the flash size is bigger than 16MiB, we can't read it from the top of 4G */
+	if (flash->chip->total_size > (16 * 1024))
+		return default_spi_read(flash, buf, start, len);
+
 	if (!data->flash) {
 		map_flash(flash);
 		data->flash = flash; /* keep a copy of flashctx for unmap() on tear-down. */
@@ -617,7 +622,7 @@ static const struct spi_master spi_master_yangtze = {
 };
 
 static const struct spi_master spi_master_promontory = {
-	.max_data_read	= MAX_DATA_READ_UNLIMITED,
+	.max_data_read	= FIFO_SIZE_YANGTZE - 3,
 	.max_data_write	= FIFO_SIZE_YANGTZE - 3,
 	.command	= spi100_spi_send_command,
 	.map_flash_region	= physmap,