diff mbox

[U-Boot,v2,01/16] sunxi: dram: Remove useless 'dramc_scan_dll_para()' function

Message ID 1407033174-24603-2-git-send-email-siarhei.siamashka@gmail.com
State Accepted
Delegated to: Hans de Goede
Headers show

Commit Message

Siarhei Siamashka Aug. 3, 2014, 2:32 a.m. UTC 
The attempt to do DRAM parameters calibration in 'dramc_scan_dll_para()'
function by trying different DLL adjustments and using the hardware
DQS gate training result as a feedback is a great source of inspiration,
but it just can't work properly the way it is implemented now. The fatal
problem of this implementation is that the DQS gating window can be
successfully found for almost every DLL delay adjustment setup that
gets tried. Thus making it unable to see any real difference between
'good' and 'bad' settings.

Also this code was supposed to be only activated by setting the highest
bit in the 'dram_tpr3' variable of the 'dram_para' struct (per-board
dram configuration). But none of the linux-sunxi devices has ever used
it for real. Basically, this code is just a dead weight.

Signed-off-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
---
Changes for v2:
   - break lines in the commit message in order not to exceed 72
     characters line limit
   - no other changes

 arch/arm/cpu/armv7/sunxi/dram.c | 125 +---------------------------------------
 1 file changed, 1 insertion(+), 124 deletions(-)
diff mbox

Patch

diff --git a/arch/arm/cpu/armv7/sunxi/dram.c b/arch/arm/cpu/armv7/sunxi/dram.c
index 0f1ceec..236eed7 100644
--- a/arch/arm/cpu/armv7/sunxi/dram.c
+++ b/arch/arm/cpu/armv7/sunxi/dram.c
@@ -321,117 +321,6 @@  static int dramc_scan_readpipe(void)
 	return 0;
 }
 
-static int dramc_scan_dll_para(void)
-{
-	struct sunxi_dram_reg *dram = (struct sunxi_dram_reg *)SUNXI_DRAMC_BASE;
-	const u32 dqs_dly[7] = {0x3, 0x2, 0x1, 0x0, 0xe, 0xd, 0xc};
-	const u32 clk_dly[15] = {0x07, 0x06, 0x05, 0x04, 0x03,
-				 0x02, 0x01, 0x00, 0x08, 0x10,
-				 0x18, 0x20, 0x28, 0x30, 0x38};
-	u32 clk_dqs_count[15];
-	u32 dqs_i, clk_i, cr_i;
-	u32 max_val, min_val;
-	u32 dqs_index, clk_index;
-
-	/* Find DQS_DLY Pass Count for every CLK_DLY */
-	for (clk_i = 0; clk_i < 15; clk_i++) {
-		clk_dqs_count[clk_i] = 0;
-		clrsetbits_le32(&dram->dllcr[0], 0x3f << 6,
-				(clk_dly[clk_i] & 0x3f) << 6);
-		for (dqs_i = 0; dqs_i < 7; dqs_i++) {
-			for (cr_i = 1; cr_i < 5; cr_i++) {
-				clrsetbits_le32(&dram->dllcr[cr_i],
-						0x4f << 14,
-						(dqs_dly[dqs_i] & 0x4f) << 14);
-			}
-			udelay(2);
-			if (dramc_scan_readpipe() == 0)
-				clk_dqs_count[clk_i]++;
-		}
-	}
-	/* Test DQS_DLY Pass Count for every CLK_DLY from up to down */
-	for (dqs_i = 15; dqs_i > 0; dqs_i--) {
-		max_val = 15;
-		min_val = 15;
-		for (clk_i = 0; clk_i < 15; clk_i++) {
-			if (clk_dqs_count[clk_i] == dqs_i) {
-				max_val = clk_i;
-				if (min_val == 15)
-					min_val = clk_i;
-			}
-		}
-		if (max_val < 15)
-			break;
-	}
-
-	/* Check if Find a CLK_DLY failed */
-	if (!dqs_i)
-		goto fail;
-
-	/* Find the middle index of CLK_DLY */
-	clk_index = (max_val + min_val) >> 1;
-	if ((max_val == (15 - 1)) && (min_val > 0))
-		/* if CLK_DLY[MCTL_CLK_DLY_COUNT] is very good, then the middle
-		 * value can be more close to the max_val
-		 */
-		clk_index = (15 + clk_index) >> 1;
-	else if ((max_val < (15 - 1)) && (min_val == 0))
-		/* if CLK_DLY[0] is very good, then the middle value can be more
-		 * close to the min_val
-		 */
-		clk_index >>= 1;
-	if (clk_dqs_count[clk_index] < dqs_i)
-		clk_index = min_val;
-
-	/* Find the middle index of DQS_DLY for the CLK_DLY got above, and Scan
-	 * read pipe again
-	 */
-	clrsetbits_le32(&dram->dllcr[0], 0x3f << 6,
-			(clk_dly[clk_index] & 0x3f) << 6);
-	max_val = 7;
-	min_val = 7;
-	for (dqs_i = 0; dqs_i < 7; dqs_i++) {
-		clk_dqs_count[dqs_i] = 0;
-		for (cr_i = 1; cr_i < 5; cr_i++) {
-			clrsetbits_le32(&dram->dllcr[cr_i],
-					0x4f << 14,
-					(dqs_dly[dqs_i] & 0x4f) << 14);
-		}
-		udelay(2);
-		if (dramc_scan_readpipe() == 0) {
-			clk_dqs_count[dqs_i] = 1;
-			max_val = dqs_i;
-			if (min_val == 7)
-				min_val = dqs_i;
-		}
-	}
-
-	if (max_val < 7) {
-		dqs_index = (max_val + min_val) >> 1;
-		if ((max_val == (7-1)) && (min_val > 0))
-			dqs_index = (7 + dqs_index) >> 1;
-		else if ((max_val < (7-1)) && (min_val == 0))
-			dqs_index >>= 1;
-		if (!clk_dqs_count[dqs_index])
-			dqs_index = min_val;
-		for (cr_i = 1; cr_i < 5; cr_i++) {
-			clrsetbits_le32(&dram->dllcr[cr_i],
-					0x4f << 14,
-					(dqs_dly[dqs_index] & 0x4f) << 14);
-		}
-		udelay(2);
-		return dramc_scan_readpipe();
-	}
-
-fail:
-	clrbits_le32(&dram->dllcr[0], 0x3f << 6);
-	for (cr_i = 1; cr_i < 5; cr_i++)
-		clrbits_le32(&dram->dllcr[cr_i], 0x4f << 14);
-	udelay(2);
-
-	return dramc_scan_readpipe();
-}
-
 static void dramc_clock_output_en(u32 on)
 {
 #if defined(CONFIG_SUN5I) || defined(CONFIG_SUN7I)
@@ -665,19 +554,7 @@  unsigned long dramc_init(struct dram_para *para)
 
 	/* scan read pipe value */
 	mctl_itm_enable();
-	if (para->tpr3 & (0x1 << 31)) {
-		ret_val = dramc_scan_dll_para();
-		if (ret_val == 0)
-			para->tpr3 =
-				(((readl(&dram->dllcr[0]) >> 6) & 0x3f) << 16) |
-				(((readl(&dram->dllcr[1]) >> 14) & 0xf) << 0) |
-				(((readl(&dram->dllcr[2]) >> 14) & 0xf) << 4) |
-				(((readl(&dram->dllcr[3]) >> 14) & 0xf) << 8) |
-				(((readl(&dram->dllcr[4]) >> 14) & 0xf) << 12
-				);
-	} else {
-		ret_val = dramc_scan_readpipe();
-	}
+	ret_val = dramc_scan_readpipe();
 
 	if (ret_val < 0)
 		return 0;