[src/trunk]: src/sys/arch/arm/rockchip Don't fail if we cannot compute the cl...

[tnn <tnn%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/9c9d9581d9c9
branches:  trunk
changeset: 970698:9c9d9581d9c9
user:      tnn <tnn%NetBSD.org@localhost>
date:      Wed Apr 01 20:37:32 2020 +0000

description:
Don't fail if we cannot compute the clock divider because the master
clock is too slow for what the slave device requested.
Instead warn and select the highest available slave clock rate.
Should fix boot hang on Pinebook Pro when using spiflash(4).

diffstat:

 sys/arch/arm/rockchip/rk_spi.c |  12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diffs (33 lines):

diff -r 6958eeb6a5de -r 9c9d9581d9c9 sys/arch/arm/rockchip/rk_spi.c
--- a/sys/arch/arm/rockchip/rk_spi.c    Wed Apr 01 20:24:50 2020 +0000
+++ b/sys/arch/arm/rockchip/rk_spi.c    Wed Apr 01 20:37:32 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rk_spi.c,v 1.3 2019/08/13 17:15:55 tnn Exp $   */
+/*     $NetBSD: rk_spi.c,v 1.4 2020/04/01 20:37:32 tnn Exp $   */
 
 /*
  * Copyright (c) 2019 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: rk_spi.c,v 1.3 2019/08/13 17:15:55 tnn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: rk_spi.c,v 1.4 2020/04/01 20:37:32 tnn Exp $");
 
 #include <sys/param.h>
 #include <sys/device.h>
@@ -277,8 +277,12 @@
        uint16_t divider;
 
        divider = (sc->sc_spi_freq / speed) & ~1;
-       if (divider < 2)
-               return EINVAL;
+       if (divider < 2) {
+               aprint_error_dev(sc->sc_dev,
+                   "spi_clk %u is too low for speed %u, using speed %u\n",
+                    sc->sc_spi_freq, speed, sc->sc_spi_freq / 2);
+               divider = 2;
+       }
 
        if (slave >= sc->sc_spi.sct_nslaves)
                return EINVAL;