linux-kernel - Re: [PATCH v9 3/3] dmaengine: ptdma: Add debugfs entries for PTDMA

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Message-ID: <9d326966-a759-5ccf-e488-e66d2119eda7@amd.com>
Date:   Tue, 15 Jun 2021 16:48:21 +0530
From:   Sanjay R Mehta <sanmehta@....com>
To:     Vinod Koul <vkoul@...nel.org>, Sanjay R Mehta <Sanju.Mehta@....com>
Cc:     gregkh@...uxfoundation.org, dan.j.williams@...el.com,
        Thomas.Lendacky@....com, Shyam-sundar.S-k@....com,
        Nehal-bakulchandra.Shah@....com, robh@...nel.org,
        mchehab+samsung@...nel.org, davem@...emloft.net,
        linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org
Subject: Re: [PATCH v9 3/3] dmaengine: ptdma: Add debugfs entries for PTDMA



On 6/9/2021 7:40 PM, Vinod Koul wrote:
> [CAUTION: External Email]
> 
> On 02-06-21, 12:22, Sanjay R Mehta wrote:
> 
>> +/* DebugFS helpers */
>> +#define      MAX_NAME_LEN    20
>> +#define      RI_VERSION_NUM  0x0000003F
>> +
>> +#define      RI_NUM_VQM      0x00078000
>> +#define      RI_NVQM_SHIFT   15
>> +
>> +static DEFINE_MUTEX(pt_debugfs_lock);
> 
> unused?
> 
>> +
>> +static int pt_debugfs_info_show(struct seq_file *s, void *p)
>> +{
>> +     struct pt_device *pt = s->private;
>> +     unsigned int regval;
>> +
>> +     if (!pt)
>> +             return 0;
> 
> better return an error code?
> 
>> +
>> +     seq_printf(s, "Device name: %s\n", pt->name);
>> +     seq_printf(s, "   # Queues: %d\n", 1);
>> +     seq_printf(s, "     # Cmds: %d\n", pt->cmd_count);
>> +
>> +     regval = ioread32(pt->io_regs + CMD_PT_VERSION);
> 
> how do you ensure your device is not sleeping or you can access iomem
> safely?
> 

This device will never go to sleep state as this DMA device is part of AMD server SOC.
Hence PM support is not implemented.

- Sanjay