linux-kernel - Re: [RFC 3/3] mailbox: pl320: Introduce common API driver

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Date:	Mon, 29 Apr 2013 22:27:41 +0530
From:	Jassi Brar <jaswinder.singh@...aro.org>
To:	Suman Anna <s-anna@...com>
Cc:	Jassi Brar <jassisinghbrar@...il.com>,
	"Loic PALLARDY (loic.pallardy@...com)" <loic.pallardy@...com>,
	Arnd Bergmann <arnd@...db.de>,
	lkml <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Andy Green <andy.green@...aro.org>,
	Mark Langsdorf <mark.langsdorf@...xeda.com>
Subject: Re: [RFC 3/3] mailbox: pl320: Introduce common API driver

On 29 April 2013 22:14, Suman Anna <s-anna@...com> wrote:
> On 04/27/2013 01:14 PM, jassisinghbrar@...il.com wrote:
>> From: Jassi Brar <jaswinder.singh@...aro.org>
>>
>> Convert the PL320 controller driver to work with the common
>> mailbox API. Also convert the only user of PL320, highbank-cpufreq.c
>> to work with thee API. Drop the obsoleted driver pl320-ipc.c
>
> I think the conversion is fine based on your API, but you have
> eliminated the stand-alone Rx interrupt code in the conversion. I
> searched for if anybody is registering these rx atomic notifiers in 3.9,
> and didn't find any. Is this expected to stay like this or is it some
> future functionality not yet added, but getting removed in this patch.
>
Yeah, probably only some out-of-tree code needed that but that made my
life simpler :)

>>
>> Signed-off-by: Jassi Brar <jaswinder.singh@...aro.org>
>> ---
>>  drivers/cpufreq/highbank-cpufreq.c       |   22 +++-
>>  drivers/mailbox/Makefile                 |    2 +-
>>  drivers/mailbox/{pl320-ipc.c => pl320.c} |  194 ++++++++++++++++--------------
>>  include/linux/pl320-ipc.h                |   17 ---
>>  4 files changed, 125 insertions(+), 110 deletions(-)
>>  rename drivers/mailbox/{pl320-ipc.c => pl320.c} (51%)
>>  delete mode 100644 include/linux/pl320-ipc.h
>>
>> diff --git a/drivers/cpufreq/highbank-cpufreq.c b/drivers/cpufreq/highbank-cpufreq.c
>> index 3118b87..5c057e0 100644
>> --- a/drivers/cpufreq/highbank-cpufreq.c
>> +++ b/drivers/cpufreq/highbank-cpufreq.c
>> @@ -19,7 +19,7 @@
>>  #include <linux/cpu.h>
>>  #include <linux/err.h>
>>  #include <linux/of.h>
>> -#include <linux/pl320-ipc.h>
>> +#include <linux/mailbox_client.h>
>>  #include <linux/platform_device.h>
>>
>>  #define HB_CPUFREQ_CHANGE_NOTE       0x80000001
>> @@ -29,8 +29,26 @@
>>  static int hb_voltage_change(unsigned int freq)
>>  {
>>       u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
>> +     struct ipc_client cl;
>> +     int ret = -ETIMEDOUT;
>> +     void *chan;
>>
>> -     return pl320_ipc_transmit(msg);
>> +     cl.rxcb = NULL;
>> +     cl.txcb = NULL;
>> +     cl.tx_block = true;
>> +     cl.tx_tout = 1000; /* 1 sec */
>> +     cl.cntlr_data = NULL;
>> +     cl.knows_txdone = false;
>> +     cl.chan_name = "pl320:A9_to_M3";
>> +
>> +     chan = ipc_request_channel(&cl);
>> +
>> +     if (ipc_send_message(chan, (void *)msg))
>> +             ret = msg[1]; /* PL320 updates buffer with FIFO after ACK */
>> +
>> +     ipc_free_channel(chan);
>
> I think I understand why you have done this, but do you really want to
> request and free every time in the highbank cpufreq driver?
>
Exactly my aim - make the API light enough to enable the client to
use-and-throw. And also because the channel are exclusively assigned,
acquire a channel only for as long as you need it.

cheers.
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