According to the MPC8555/MPC8541 reference manual the SS_EN (source synchronous enable) bit in the DDR_SDRAM_CLK_CNLT register must be set during initialization.
From section 9.4.1.8 of that manual:
Source synchronous enable. This bit field must be set during initialization. See Section 9.6.1, "DDR SDRAM Initialization Sequence," details.
0 - Reserved 1 - The address and command are sent to the DDR SDRAMs source synchronously.
In addition, Freescale application note AN2805 is also very clear that this bit must be set.
This patch reverts a change introduced by commit 457caecdbca3df21a93abff19eab12dbc61b7897.
Testing Done:
Compiled targets CONFIG_TARGET_MPC8555CDS and CONFIG_TARGET_MPC8541CDS and inspected the generated assembly code to verify the SS_EN bit was being set. There is one extra instruction emitted:
fff9b774: 65 29 80 00 oris r9,r9,32768
Compiled the CONFIG_TARGET_MPC8548CDS target and verified that no additional instructions were emitted related to this patch.
Booted an image on a MPC8541 based board successfully.
Signed-off-by: Curt Brune curt@cumulusnetworks.com --- drivers/ddr/fsl/ctrl_regs.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/ddr/fsl/ctrl_regs.c b/drivers/ddr/fsl/ctrl_regs.c index 03d7ff1..6bdc47e 100644 --- a/drivers/ddr/fsl/ctrl_regs.c +++ b/drivers/ddr/fsl/ctrl_regs.c @@ -1730,13 +1730,21 @@ static void set_ddr_data_init(fsl_ddr_cfg_regs_t *ddr) */ static void set_ddr_sdram_clk_cntl(fsl_ddr_cfg_regs_t *ddr, const memctl_options_t *popts) { unsigned int clk_adjust; /* Clock adjust */ + unsigned int ss_en = 0; /* Source synchronous enable */
+#if defined(CONFIG_MPC8541) || defined(CONFIG_MPC8555) + /* Per FSL Application Note: AN2805 */ + ss_en = 1; +#endif clk_adjust = popts->clk_adjust; - ddr->ddr_sdram_clk_cntl = (clk_adjust & 0xF) << 23; + ddr->ddr_sdram_clk_cntl = (0 + | ((ss_en & 0x1) << 31) + | ((clk_adjust & 0xF) << 23) + ); debug("FSLDDR: clk_cntl = 0x%08x\n", ddr->ddr_sdram_clk_cntl); }
/* DDR Initialization Address (DDR_INIT_ADDR) */ static void set_ddr_init_addr(fsl_ddr_cfg_regs_t *ddr)