[2/2] mmc: rtsx: modify phase searching method for tunning

Commit Message

[e-mail] Nov. 19, 2013, 11:10 a.m. UTC

From: Micky Ching <[e-mail]>

The new phase searching method is more concise and easier to
understand.

Signed-off-by: Micky Ching <[e-mail]>
---
 drivers/mmc/host/rtsx_pci_sdmmc.c |  108 +++++++++++--------------------------
 1 file changed, 30 insertions(+), 78 deletions(-)

Comments

Dan Carpenter Nov. 20, 2013, 8:17 a.m. UTC | #1

On Tue, Nov 19, 2013 at 07:10:35PM +0800, [e-mail] wrote:
> -static u8 sd_search_final_phase(struct realtek_pci_sdmmc *host, u32 phase_map)
> +static inline u32 sd_get_phase_point(u32 phase_map, unsigned int idx)
>  {
> -	struct timing_phase_path path[MAX_PHASE + 1];
> -	int i, j, cont_path_cnt;
> -	int new_block, max_len, final_path_idx;
> -	u8 final_phase = 0xFF;
> +	idx &= MAX_PHASE;
> +	return phase_map & (1 << idx);
> +}
> +

This function is confusing....

MAX_PHASE is a terrible name.  It's in a global header but it doesn't
have a prefix.  It should be #define RTS_MAX_PHASE.  It's weird that we
are using it both as a number and as bit mask.  It's weird that we
always add a "+ 1" to MAX_PHASE.  It means the name is chosen poorly.
Maybe it should be:

#define RTS_MAX_PHASE  32
#define RTS_PHASE_MASK 0x1f

So this function takes a phase_map and an index and it wraps the index
by masking away the top bits then it tests to see if the wrapped index
bit is set?  The wrapping is very strange.

The name of the function is sd_get_phase_point() but we only test to
see if it returns zero.  The name of the function is not helpful.
"sd" is a generic prefix.
"get" is misleading because we don't "get" anything it only returns zero
on success?
"phase_point" might be helpful but I don't know what a phase_point is.
Add a comment about that maybe.

regards,
dan carpenter

--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[e-mail] Nov. 20, 2013, 9:13 a.m. UTC | #2

Hi Dan:
On 11/20/2013 04:17 PM, Dan Carpenter wrote:
> On Tue, Nov 19, 2013 at 07:10:35PM +0800, [e-mail] wrote:
>> -static u8 sd_search_final_phase(struct realtek_pci_sdmmc *host, u32 phase_map)
>> +static inline u32 sd_get_phase_point(u32 phase_map, unsigned int idx)
>>   {
>> -	struct timing_phase_path path[MAX_PHASE + 1];
>> -	int i, j, cont_path_cnt;
>> -	int new_block, max_len, final_path_idx;
>> -	u8 final_phase = 0xFF;
>> +	idx &= MAX_PHASE;
>> +	return phase_map & (1 << idx);
>> +}
>> +
> This function is confusing....
>
> MAX_PHASE is a terrible name.  It's in a global header but it doesn't
> have a prefix.  It should be #define RTS_MAX_PHASE.  It's weird that we
> are using it both as a number and as bit mask.  It's weird that we
> always add a "+ 1" to MAX_PHASE.  It means the name is chosen poorly.
> Maybe it should be:
>
> #define RTS_MAX_PHASE  32
> #define RTS_PHASE_MASK 0x1f
That's good, I will modify and resend.
> So this function takes a phase_map and an index and it wraps the index
> by masking away the top bits then it tests to see if the wrapped index
> bit is set?  The wrapping is very strange.
We use this function to find whether the bit of index in the phase_map
is 1. The index can be twice as MAX_PHASE(reach to 63), because we use
a unidirectional search, start search continuous phase to found the
max continuous length from 0, 1, ..., to 31. When we start from
bit31, index 32 should wrap as 0. This function can be replaced by mod
function(idx %= MAX_PHASE + 1).
> The name of the function is sd_get_phase_point() but we only test to
> see if it returns zero.  The name of the function is not helpful.
> "sd" is a generic prefix.
> "get" is misleading because we don't "get" anything it only returns zero
> on success?
> "phase_point" might be helpful but I don't know what a phase_point is.
> Add a comment about that maybe.
Yes, thank you for your suggestion, the function name is really not good.
I want use test_phase_bit(u32 phase_map, unsigned int bit), is that ok?
> regards,
> dan carpenter
>
> .
>

Patch

diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
index c9a7328..fb2f159 100644
--- a/drivers/mmc/host/rtsx_pci_sdmmc.c
+++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
@@ -31,16 +31,6 @@ 
 #include <linux/mfd/rtsx_pci.h>
 #include <asm/unaligned.h>
 
-/* SD Tuning Data Structure
- * Record continuous timing phase path
- */
-struct timing_phase_path {
-	int start;
-	int end;
-	int mid;
-	int len;
-};
-
 struct realtek_pci_sdmmc {
 	struct platform_device	*pdev;
 	struct rtsx_pcr		*pcr;
@@ -511,85 +501,47 @@  static int sd_change_phase(struct realtek_pci_sdmmc *host,
 	return 0;
 }
 
-static u8 sd_search_final_phase(struct realtek_pci_sdmmc *host, u32 phase_map)
+static inline u32 sd_get_phase_point(u32 phase_map, unsigned int idx)
 {
-	struct timing_phase_path path[MAX_PHASE + 1];
-	int i, j, cont_path_cnt;
-	int new_block, max_len, final_path_idx;
-	u8 final_phase = 0xFF;
+	idx &= MAX_PHASE;
+	return phase_map & (1 << idx);
+}
+
+static int sd_get_phase_len(u32 phase_map, unsigned int idx)
+{
+	int i;
 
-	/* Parse phase_map, take it as a bit-ring */
-	cont_path_cnt = 0;
-	new_block = 1;
-	j = 0;
 	for (i = 0; i < MAX_PHASE + 1; i++) {
-		if (phase_map & (1 << i)) {
-			if (new_block) {
-				new_block = 0;
-				j = cont_path_cnt++;
-				path[j].start = i;
-				path[j].end = i;
-			} else {
-				path[j].end = i;
-			}
-		} else {
-			new_block = 1;
-			if (cont_path_cnt) {
-				/* Calculate path length and middle point */
-				int idx = cont_path_cnt - 1;
-				path[idx].len =
-					path[idx].end - path[idx].start + 1;
-				path[idx].mid =
-					path[idx].start + path[idx].len / 2;
-			}
-		}
+		if (sd_get_phase_point(phase_map, idx + i) == 0)
+			return i;
 	}
+	return MAX_PHASE + 1;
+}
 
-	if (cont_path_cnt == 0) {
-		dev_dbg(sdmmc_dev(host), "No continuous phase path\n");
-		goto finish;
-	} else {
-		/* Calculate last continuous path length and middle point */
-		int idx = cont_path_cnt - 1;
-		path[idx].len = path[idx].end - path[idx].start + 1;
-		path[idx].mid = path[idx].start + path[idx].len / 2;
-	}
+static u8 sd_search_final_phase(struct realtek_pci_sdmmc *host, u32 phase_map)
+{
+	int start = 0, len = 0;
+	int start_final = 0, len_final = 0;
+	u8 final_phase = 0xFF;
 
-	/* Connect the first and last continuous paths if they are adjacent */
-	if (!path[0].start && (path[cont_path_cnt - 1].end == MAX_PHASE)) {
-		/* Using negative index */
-		path[0].start = path[cont_path_cnt - 1].start - MAX_PHASE - 1;
-		path[0].len += path[cont_path_cnt - 1].len;
-		path[0].mid = path[0].start + path[0].len / 2;
-		/* Convert negative middle point index to positive one */
-		if (path[0].mid < 0)
-			path[0].mid += MAX_PHASE + 1;
-		cont_path_cnt--;
+	if (phase_map == 0) {
+		dev_dbg(sdmmc_dev(host), "Phase: [map:%x]\n", phase_map);
+		return final_phase;
 	}
 
-	/* Choose the longest continuous phase path */
-	max_len = 0;
-	final_phase = 0;
-	final_path_idx = 0;
-	for (i = 0; i < cont_path_cnt; i++) {
-		if (path[i].len > max_len) {
-			max_len = path[i].len;
-			final_phase = (u8)path[i].mid;
-			final_path_idx = i;
+	while (start < MAX_PHASE + 1) {
+		len = sd_get_phase_len(phase_map, start);
+		if (len_final < len) {
+			start_final = start;
+			len_final = len;
 		}
-
-		dev_dbg(sdmmc_dev(host), "path[%d].start = %d\n",
-				i, path[i].start);
-		dev_dbg(sdmmc_dev(host), "path[%d].end = %d\n",
-				i, path[i].end);
-		dev_dbg(sdmmc_dev(host), "path[%d].len = %d\n",
-				i, path[i].len);
-		dev_dbg(sdmmc_dev(host), "path[%d].mid = %d\n",
-				i, path[i].mid);
+		start += len ? len : 1;
 	}
 
-finish:
-	dev_dbg(sdmmc_dev(host), "Final chosen phase: %d\n", final_phase);
+	final_phase = (start_final + len_final / 2) & MAX_PHASE;
+	dev_dbg(sdmmc_dev(host), "Phase: [map:%x] [maxlen:%d] [final:%d]\n",
+		phase_map, len_final, final_phase);
+
 	return final_phase;
 }