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staging: sm750fb: skip unnecessary comparisons

PATCH In review Lynn Lei 2 participants 2 messages Jul 3, 2017

Subsystems (3)
Staging Framebuffer layer Staging - silicon motion SM750 frame buffer driver
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Lynn Lei

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#0 lore raw

PATCH 1/1 staging: sm750fb: skip unnecessary comparisons

introduced early checks to skip unnecessary comparisons when flags set.

Signed-off-by Lynn Lei <[email protected]>
---
 drivers/staging/sm750fb/sm750.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
drivers/staging/sm750fb/sm750.c +8 -3
index 386d4adcd91d..9e57a2d32465 100644
@@ -1171,11 +1171,16 @@ static int __init lynxfb_setup(char *options)
 	 */
 	while ((opt = strsep(&options, ":")) != NULL) {
 		/* options that mean for any lynx chips are configured here */
-		if (!strncmp(opt, "noaccel", strlen("noaccel"))) {
+
+		/*
+		 * NOTE: the length of options is hard-coded
+		 * if any of those options changed  please update its length
+		 */
+		if (!g_noaccel && !strncmp(opt, "noaccel", 7)) {
 			g_noaccel = 1;
-		} else if (!strncmp(opt, "nomtrr", strlen("nomtrr"))) {
+		} else if (!g_nomtrr && !strncmp(opt, "nomtrr", 6)) {
 			g_nomtrr = 1;
-		} else if (!strncmp(opt, "dual", strlen("dual"))) {
+		} else if (!g_dualview && !strncmp(opt, "dual", 4)) {
 			g_dualview = 1;
 		} else {
 			strcat(tmp, opt);
Signature · 1 line
2.13.2
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#1 lore raw
Quoted 1 line · Lynn Lei

introduced early checks to skip unnecessary comparisons when flags set.

Why?

Quoted 11 lines
Signed-off-by Lynn Lei <[email protected]>
---
 drivers/staging/sm750fb/sm750.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
drivers/staging/sm750fb/sm750.c +0 -0
index 386d4adcd91d..9e57a2d32465 100644

drivers/staging/sm750fb/sm750.c static int __init lynxfb_setup(char *options) · line 1178

Quoted 9 lines
drivers/staging/sm750fb/sm750.c +5 -1
@@ -1171,11 +1171,16 @@ static int __init lynxfb_setup(char *options)
 	 */
 	while ((opt = strsep(&options, ":")) != NULL) {
 		/* options that mean for any lynx chips are configured here */
-		if (!strncmp(opt, "noaccel", strlen("noaccel"))) {
+
+		/*
+		 * NOTE: the length of options is hard-coded
+		 * if any of those options changed  please update its length
+		 */

That's not good, why require this? What is wrong with the original code here? It doesn't have that type of restriction, right?

drivers/staging/sm750fb/sm750.c static int __init lynxfb_setup(char *options) · line 1181

Quoted 4 lines
drivers/staging/sm750fb/sm750.c +2 -1
+		if (!g_noaccel && !strncmp(opt, "noaccel", 7)) {
 			g_noaccel = 1;
-		} else if (!strncmp(opt, "nomtrr", strlen("nomtrr"))) {
+		} else if (!g_nomtrr && !strncmp(opt, "nomtrr", 6)) {

I don't see the benefit of this change at all, what am I missing?

thanks,

greg k-h