bcm27xx: remove linux 5.10 compatibility

[openwrt/staging/chunkeey.git] / target / linux / bcm27xx / patches-5.10 / 950-0448-spi-bcm2835-Workaround-fix-for-zero-length-transfers.patch

diff --git a/target/linux/bcm27xx/patches-5.10/950-0448-spi-bcm2835-Workaround-fix-for-zero-length-transfers.patch b/target/linux/bcm27xx/patches-5.10/950-0448-spi-bcm2835-Workaround-fix-for-zero-length-transfers.patch
deleted file mode 100644 (file)
index 2b9d30f..0000000
--- a/target/linux/bcm27xx/patches-5.10/950-0448-spi-bcm2835-Workaround-fix-for-zero-length-transfers.patch
+++ /dev/null
@@ -1,50 +0,0 @@
-From 54545710d40fd00e3c727603a446500b1b9b3d88 Mon Sep 17 00:00:00 2001
-From: Phil Elwell <phil@raspberrypi.com>
-Date: Thu, 28 Jan 2021 11:30:04 +0000
-Subject: [PATCH] spi: bcm2835: Workaround/fix for zero-length
- transfers
-
-A relatively recent commit ([1]) contained optimisation for the PIO
-SPI FIFO-filling functions. The commit message includes the phrase
-"[t]he blind and counted loops are always called with nonzero count".
-This is technically true, but it is still possible for count to become
-zero before the loop is entered - if tfr->len is zero. Moving the loop
-exit condition to the end of the loop saves a few cycles, but results
-in a near-infinite loop should the revised count be zero on entry.
-
-Strangely, zero-lengthed transfers aren't filtered by the SPI framework
-and, even more strangely, the Python3 spidev library is triggering them
-for no obvious reason.
-
-Avoid the problem completely by bailing out of the main transfer
-function early if trf->len is zero, although there may be a case for
-moving the mitigation into the framework.
-
-See: https://github.com/raspberrypi/linux/issues/4100
-
-Signed-off-by: Phil Elwell <phil@raspberrypi.com>
-
-[1] 26751de25d25 ("spi: bcm2835: Micro-optimise FIFO loops")
----
- drivers/spi/spi-bcm2835.c | 10 ++++++++++
- 1 file changed, 10 insertions(+)
-
---- a/drivers/spi/spi-bcm2835.c
-+++ b/drivers/spi/spi-bcm2835.c
-@@ -1092,6 +1092,16 @@ static int bcm2835_spi_transfer_one(stru
-       unsigned long hz_per_byte, byte_limit;
-       u32 cs = bs->prepare_cs[spi->chip_select];
- 
-+      if (unlikely(!tfr->len)) {
-+              static int warned;
-+
-+              if (!warned)
-+                      dev_warn(&spi->dev,
-+                               "zero-length SPI transfer ignored\n");
-+              warned = 1;
-+              return 0;
-+      }
-+
-       /* set clock */
-       spi_hz = tfr->speed_hz;
-