linux-kernel - Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel

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Message-ID: <yw1x1tai9yud.fsf@unicorn.mansr.com>
Date:	Sat, 19 Dec 2015 16:39:54 +0000
From:	Måns Rullgård <mans@...sr.com>
To:	Julian Margetson <runaway@...dw.ms>
Cc:	Andy Shevchenko <andy.shevchenko@...il.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Tejun Heo <tj@...nel.org>, linux-ide@...r.kernel.org,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel

Julian Margetson <runaway@...dw.ms> writes:

> On 12/19/2015 11:40 AM, Måns Rullgård wrote:
>> OK, I've found something.  The dma setup errors are benign, caused by
>> the driver calling dmaengine_prep_slave_sg() even for non-dma
>> operations.  The real error is the lock recursion that's reported
>> later.  I wasn't seeing it since I was running a UP non-preempt kernel.
>> With lock debugging enabled, I get the same error.  This patch should
>> fix it.
>>
>> ---8<---
>> >From 94c4769d2171ce66079fd486a45e09dd64db62c0 Mon Sep 17 00:00:00 2001
>> From: Mans Rullgard<mans@...sr.com>
>> Date: Sat, 19 Dec 2015 15:26:23 +0000
>> Subject: [PATCH] ata: sata_dwc_460ex: remove incorrect locking
>>
>> This lock is already taken in ata_scsi_queuecmd() a few levels up the
>> call stack so attempting to take it here is an error.  Moreover, it is
>> pointless in the first place since it only protects a single, atomic
>> assignment.
>>
>> Signed-off-by: Mans Rullgard<mans@...sr.com>
>> ---
>>   drivers/ata/sata_dwc_460ex.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
>> index 799df86..5696f39 100644
>> --- a/drivers/ata/sata_dwc_460ex.c
>> +++ b/drivers/ata/sata_dwc_460ex.c
>> @@ -1001,16 +1001,14 @@ static void sata_dwc_exec_command_by_tag(struct ata_port *ap,
>>   					 struct ata_taskfile *tf,
>>   					 u8 tag, u32 cmd_issued)
>>   {
>> -	unsigned long flags;
>>   	struct sata_dwc_device_port *hsdevp = HSDEVP_FROM_AP(ap);
>>   	struct sata_dwc_device *hsdev = HSDEV_FROM_AP(ap);
>>     	dev_dbg(ap->dev, "%s cmd(0x%02x): %s tag=%d\n", __func__,
>> tf->command,
>>   		ata_get_cmd_descript(tf->command), tag);
>>   -	spin_lock_irqsave(&ap->host->lock, flags);
>>   	hsdevp->cmd_issued[tag] = cmd_issued;
>> -	spin_unlock_irqrestore(&ap->host->lock, flags);
>> +
>>   	/*
>>   	 * Clear SError before executing a new command.
>>   	 * sata_dwc_scr_write and read can not be used here. Clearing the PM
> having a problem applying the patch .
>
> patching file drivers/ata/sata_dwc_460ex.c
> Hunk #1 FAILED at 1001 (different line endings).

OK, attaching it instead.

-- 
Måns Rullgård

View attachment "0001-ata-sata_dwc_460ex-remove-incorrect-locking.patch" of type "text/x-diff" (1429 bytes)