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The following commit(s) were added to refs/heads/master by this push:
new d9d6491 drivers/leds/ws2812: optimize reset bytes
d9d6491 is described below
commit d9d649105d179ca82ceefd22ad5d10ba66d8934e
Author: Diego Herranz <diegoherr...@diegoherranz.com>
AuthorDate: Wed Dec 9 09:36:15 2020 +0000
drivers/leds/ws2812: optimize reset bytes
It's not necessary to send a reset pulse after sending the RGB data
since the first thing that a new transmission does is sending the long
reset pulse. I have left 1 reset byte after the RGB data to keep some
padding given that the bits inside the byte are shifted by 1 bit although
I think it wouldn't be necessary either. But just in case.
This reduces the memory usage (you can easily save 60 bytes) and increases
the maximum refresh rate.
---
drivers/leds/ws2812.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/leds/ws2812.c b/drivers/leds/ws2812.c
index bc58f9d..867a183 100644
--- a/drivers/leds/ws2812.c
+++ b/drivers/leds/ws2812.c
@@ -78,17 +78,17 @@
#define WS2812_RW_PIXEL_SIZE 4
/* Transmit buffer looks like:
- * [<----reset bytes---->|<-RGBn->...<-RGB0->|<----reset bytes---->]
+ * [<----N reset bytes---->|<-RGBn->...<-RGB0->|<----1 reset byte---->]
*
* It is important that this is shipped as close to one chunk as possible
* in order to meet timing requirements and to keep MOSI from going high
* between transactions. Some chips will leave MOSI at the state of the
* MSB of the last byte for this reason it is recommended to shift the
* bits that represents the zero or one waveform so that the MSB is 0.
- * The reset clocks will pad the shortened low at the end.
+ * The reset byte after the RGB data will pad the shortened low at the end.
*/
-#define TXBUFF_SIZE(n) (WS2812_RST_CYCLES * 2 + n * WS2812_BYTES_PER_LED)
+#define TXBUFF_SIZE(n) (WS2812_RST_CYCLES + n * WS2812_BYTES_PER_LED + 1)
/****************************************************************************
* Private Types
