On 02/09/2017 02:32 AM, Thomas Schaefer wrote:
Hi York,
When compiling latest u-boot with gcc 6.3 compiler, I get several 'unused-const-variable' warnings in options.c file of FSL DDR driver. Affected variables are for (DIMM_SLOTS_PER_CTLR==2) configuration (e.g. dual_0S[4]) and warnings could be fixed with the patch applied.
What do you think?
Thomas,
Thanks for bringing it to my attention. I understand GCC 6 may have more warnings. The proposed patch is OK in logic but it increases the size of code unnecessarily. Can you come up with a different fix?
I can come back to check after I finish my work on hand.
York
Hi York,
not sure if I understand this correctly, but why is code size increased when these variables are not defined? I think code size is decreased instead as these variables are no longer defined if not needed.
I also don't see a way to achieve this in a different way as the variables are defined differently for DDR2, DDR3 and DDR4.
Wait a minute, did you generate the patch backward? Your patch shows removing "#if CONFIG_DIMM_SLOTS_PER_CTLR==2" which doesn't exist in current code. If the logic is reversed, then yes, you are reducing the size. Can GCC 6 optimize out the unused data? If yes, maybe we can use __maybe_unused to get rid of the warning?
York
Oops, you are right, sorry for the confusion. Here's the corrected version:
diff --git a/drivers/ddr/fsl/options.c b/drivers/ddr/fsl/options.c index d6a8fcb216..d90ed0b6cc 100644 --- a/drivers/ddr/fsl/options.c +++ b/drivers/ddr/fsl/options.c @@ -89,6 +89,7 @@ static const struct dynamic_odt single_S[4] = { {0, 0, 0, 0}, };
+#if (CONFIG_DIMM_SLOTS_PER_CTLR==2) static const struct dynamic_odt dual_DD[4] = { { /* cs0 */ FSL_DDR_ODT_NEVER, @@ -235,6 +236,7 @@ static const struct dynamic_odt dual_0S[4] = { {0, 0, 0, 0}
}; +#endif
static const struct dynamic_odt odt_unknown[4] = { { /* cs0 */ @@ -319,6 +321,7 @@ static const struct dynamic_odt single_S[4] = { {0, 0, 0, 0}, };
+#if (CONFIG_DIMM_SLOTS_PER_CTLR==2) static const struct dynamic_odt dual_DD[4] = { { /* cs0 */ FSL_DDR_ODT_NEVER, @@ -465,6 +468,7 @@ static const struct dynamic_odt dual_0S[4] = { {0, 0, 0, 0}
}; +#endif
static const struct dynamic_odt odt_unknown[4] = { { /* cs0 */ @@ -529,6 +533,7 @@ static const struct dynamic_odt single_S[4] = { {0, 0, 0, 0}, };
+#if (CONFIG_DIMM_SLOTS_PER_CTLR==2) static const struct dynamic_odt dual_DD[4] = { { /* cs0 */ FSL_DDR_ODT_OTHER_DIMM, @@ -676,6 +681,7 @@ static const struct dynamic_odt dual_0S[4] = { {0, 0, 0, 0}
}; +#endif
static const struct dynamic_odt odt_unknown[4] = { { /* cs0 */
Best regards, Thomas