[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/a89b67a6566e
branches:  trunk
changeset: 1008733:a89b67a6566e
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 1f557a90b20e -r a89b67a6566e 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;