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

["Måns Rullgård" <mans@mansr.com>]

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Julian Margetson <runaway@candw.ms> writes:

> On 12/19/2015 1:05 PM, Måns Rullgård wrote:
>> Andy Shevchenko <andy.shevchenko@gmail.com> writes:
>>
>>> On Sat, Dec 19, 2015 at 5:40 PM, Måns Rullgård <mans@mansr.com> 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.
>>> I suppose the following is a quick fix to avoid preparing descriptor
>>> for non-DMA operations (not tested anyhow)
>>>
>>> a/drivers/ata/sata_dwc_460ex.c
>>> +++ b/drivers/ata/sata_dwc_460ex.c
>>> @@ -1041,6 +1041,9 @@ static void sata_dwc_qc_prep_by_tag(struct
>>> ata_queued_cmd *qc, u8 tag)
>>>                  __func__, ap->port_no, get_dma_dir_descript(qc->dma_dir),
>>>                   qc->n_elem);
>>>
>>> +       if (!is_slave_direction(qc->dma_dir))
>>> +               return;
>>> +
>>>          desc = dma_dwc_xfer_setup(qc);
>>>          if (!desc) {
>>>                  dev_err(ap->dev, "%s: dma_dwc_xfer_setup returns NULL\n",
>> I already have a better patch sitting here.
>>
>>>> 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.
>>>> -       spin_lock_irqsave(&ap->host->lock, flags);
>>>>          hsdevp->cmd_issued[tag] = cmd_issued;
>>>> -       spin_unlock_irqrestore(&ap->host->lock, flags);
>>>> +
>>> This will create a second empty line, though I don't care it is so minor.
>> The patch leaves one blank line before the following block comment.  I
>> think it looks better that way.
>>
>
> Still can't get the patch applied .

Sorry, didn't realise it conflicted with an intervening patch I had in
my tree.  Try this one.

-- 
Måns Rullgård

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>From 97c1cdb8a6b933bad2c35b9461c2c15935f2a514 Mon Sep 17 00:00:00 2001
From: Mans Rullgard <mans@mansr.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@mansr.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 9985749..19d1c5e 100644
--- a/drivers/ata/sata_dwc_460ex.c
+++ b/drivers/ata/sata_dwc_460ex.c
@@ -995,15 +995,13 @@ 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);
 
 	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
-- 
2.6.3