diff --git a/common/cmd_sf.c b/common/cmd_sf.c
index 4af0f0af26..3f60979ae7 100644
--- a/common/cmd_sf.c
+++ b/common/cmd_sf.c
@@ -152,8 +152,10 @@ static const char *spi_flash_update_block(struct spi_flash *flash, u32 offset,
 {
 	debug("offset=%#x, sector_size=%#x, len=%#zx\n",
 	      offset, flash->sector_size, len);
-	if (spi_flash_read(flash, offset, len, cmp_buf))
+	/* Read the entire sector so to allow for rewriting */
+	if (spi_flash_read(flash, offset, flash->sector_size, cmp_buf))
 		return "read";
+	/* Compare only what is meaningful (len) */
 	if (memcmp(cmp_buf, buf, len) == 0) {
 		debug("Skip region %x size %zx: no change\n",
 		      offset, len);
@@ -163,8 +165,17 @@ static const char *spi_flash_update_block(struct spi_flash *flash, u32 offset,
 	/* Erase the entire sector */
 	if (spi_flash_erase(flash, offset, flash->sector_size))
 		return "erase";
+	/* Write the initial part of the block from the source */
 	if (spi_flash_write(flash, offset, len, buf))
 		return "write";
+	/* If it's a partial sector, rewrite the existing part */
+	if (len != flash->sector_size) {
+		/* Rewrite the original data to the end of the sector */
+		if (spi_flash_write(flash, offset + len,
+				    flash->sector_size - len, &cmp_buf[len]))
+			return "write";
+	}
+
 	return NULL;
 }
 
diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
index 3cf7142f5a..2b9f395a97 100644
--- a/drivers/spi/mxs_spi.c
+++ b/drivers/spi/mxs_spi.c
@@ -56,8 +56,6 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 				  unsigned int max_hz, unsigned int mode)
 {
 	struct mxs_spi_slave *mxs_slave;
-	struct mxs_ssp_regs *ssp_regs;
-	int reg;
 
 	if (!spi_cs_is_valid(bus, cs)) {
 		printf("mxs_spi: invalid bus %d / chip select %d\n", bus, cs);
@@ -74,13 +72,7 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 	mxs_slave->max_khz = max_hz / 1000;
 	mxs_slave->mode = mode;
 	mxs_slave->regs = mxs_ssp_regs_by_bus(bus);
-	ssp_regs = mxs_slave->regs;
 
-	reg = readl(&ssp_regs->hw_ssp_ctrl0);
-	reg &= ~(MXS_SSP_CHIPSELECT_MASK);
-	reg |= cs << MXS_SSP_CHIPSELECT_SHIFT;
-
-	writel(reg, &ssp_regs->hw_ssp_ctrl0);
 	return &mxs_slave->slave;
 
 err_init:
@@ -102,7 +94,9 @@ int spi_claim_bus(struct spi_slave *slave)
 
 	mxs_reset_block(&ssp_regs->hw_ssp_ctrl0_reg);
 
-	writel(SSP_CTRL0_BUS_WIDTH_ONE_BIT, &ssp_regs->hw_ssp_ctrl0);
+	writel((slave->cs << MXS_SSP_CHIPSELECT_SHIFT) |
+	       SSP_CTRL0_BUS_WIDTH_ONE_BIT,
+	       &ssp_regs->hw_ssp_ctrl0);
 
 	reg = SSP_CTRL1_SSP_MODE_SPI | SSP_CTRL1_WORD_LENGTH_EIGHT_BITS;
 	reg |= (mxs_slave->mode & SPI_CPOL) ? SSP_CTRL1_POLARITY : 0;