Support for Blokas Labs pisound board.

[gtrainavicius]

This pull request integrates the pisound kernel module (https://github.com/BlokasLabs/pisound/) to Raspberry Pi kernel. The out-of-tree module code was successfully tested on multiple kinds of Raspberry Pi hardware by our beta testers.

Also I tested the module integrated to kernel code too, it builds and runs as expected, the code and device tree are exactly the same as in the out-of-tree code, apart from the code being amalgamated into a single source file.

Thank you!

[pelwell]

I've add a patch to fix the README formatting. scripts/checkpatch.pl complains about a few formatting issues with the driver (C++ comments, line length, brace position and usage etc.), but if you can fix those I'll happily merge it.

It's nice to see MIDI support - it takes me back to 1985 when I first started playing with it.

[gtrainavicius]

Great! Didn't notice the requirement for running the scripts/checkpatch.pl, can you point me to any place listing the requirements for kernel patches, for future reference?

I will let you know as soon as I get the warnings fixed.

[popcornmix]

https://www.kernel.org/doc/Documentation/SubmittingPatches

[gtrainavicius]

I have fixed most of the warnings, only these two remain:

WARNING: DT compatible string "blokaslabs,pisound" appears un-documented -- check ./Documentation/devicetree/bindings/
#656: FILE: sound/soc/bcm/pisound.c:656:
+       { .compatible = "blokaslabs,pisound", },

WARNING: DT compatible string "blokaslabs,pisound-spi" appears un-documented -- check ./Documentation/devicetree/bindings/
#657: FILE: sound/soc/bcm/pisound.c:657:
+       { .compatible = "blokaslabs,pisound-spi", },

total: 0 errors, 2 warnings, 987 lines checked

I am not sure what would be the expected way to document them, also didn't find examples of other sound cards documenting them...

Is solving these warnings optional?

I have also successfully tested the updated code, the changes work as expected.

[pelwell]

No, you don't need to worry about those. I'll cast an eye over the result when I'm not on a phone, but then I'll almost certainly merge it.

[gtrainavicius]

Thank you!

[clivem]

In file included from include/linux/printk.h:6:0,
                 from include/linux/kernel.h:13,
                 from include/linux/list.h:8,
                 from include/linux/module.h:9,
                 from sound/soc/bcm/pisound.c:22:
sound/soc/bcm/pisound.c: In function 'pisnd_midi_recv_callback':
include/linux/kern_levels.h:4:18: warning: format '%x' expects argument of type 'unsigned int', but argument 2 has type 'uint8_t * {aka unsigned char *}' [-Wformat=]
 #define KERN_SOH "\001"  /* ASCII Start Of Header */
                  ^
include/linux/kern_levels.h:8:20: note: in expansion of macro 'KERN_SOH'
 #define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */
                    ^~~~~~~~
include/linux/printk.h:248:9: note: in expansion of macro 'KERN_ALERT'
  printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
         ^~~~~~~~~~
sound/soc/bcm/pisound.c:59:22: note: in expansion of macro 'pr_alert'
 # define printd(...) pr_alert(PISOUND_LOG_PREFIX __VA_ARGS__)
                      ^~~~~~~~
sound/soc/bcm/pisound.c:122:3: note: in expansion of macro 'printd'
   printd("midi recv 0x%02x, res = %d\n", data, res);
   ^~~~~~

[gtrainavicius]

Sorry about that... This code is compiled / printed only when DEBUG is defined. I will make a fix for the warning and additionally change the macro used to enable this module's debug info, as it is relevant only for the module developers only.

I will submit a patch ASAP.

[clivem]

No worries. Just noticed the warning after running a build.
Yes, I do define subdir-ccflags-y := -DDEBUG in sound/soc/Makefile

[gtrainavicius]

Alright, here is the fix, let me know if I should create a new pull request instead:

(created the patch file using: git format-patch -1 HEAD --stdout > pisound_warning_fix.patch)

pisound_warning_fix.zip

From 4824a86bda07ac2bbc0dab45dabf52979e221bca Mon Sep 17 00:00:00 2001
From: Giedrius Trainavicius <[email protected]>
Date: Tue, 25 Oct 2016 01:47:20 +0300
Subject: [PATCH] pisound: Fixed a warning on DEBUG builds and changed the
 macro that enables debug level printing from DEBUG to PISOUND_DEBUG

---
 sound/soc/bcm/pisound.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/soc/bcm/pisound.c b/sound/soc/bcm/pisound.c
index b156e57..a3cd089 100644
--- a/sound/soc/bcm/pisound.c
+++ b/sound/soc/bcm/pisound.c
@@ -55,7 +55,7 @@ static void pisnd_midi_uninit(void);

 #define PISOUND_LOG_PREFIX "pisound: "

-#ifdef DEBUG
+#ifdef PISOUND_DEBUG
 #  define printd(...) pr_alert(PISOUND_LOG_PREFIX __VA_ARGS__)
 #else
 #  define printd(...) do {} while (0)
@@ -119,7 +119,7 @@ static void pisnd_midi_recv_callback(void *substream)
    while ((n = pisnd_spi_recv(data, sizeof(data)))) {
        int res = snd_rawmidi_receive(substream, data, n);
        (void)res;
-       printd("midi recv 0x%02x, res = %d\n", data, res);
+       printd("midi recv %u bytes, res = %d\n", n, res);
    }
 }

-- 
2.1.4

[pelwell]

I've applied that patch (editing the commit message for line length).

[clivem]

Cool! I'm sure you don't need me to state the obvious, but with the patch, compile warning is resolved! ;)