From: Greg KH <gregkh@linuxfoundation.org>
To: Vinod Koul <vkoul@kernel.org>
Cc: Sanjay R Mehta <sanmehta@amd.com>,
Sanjay R Mehta <Sanju.Mehta@amd.com>,
dan.j.williams@intel.com, Thomas.Lendacky@amd.com,
Shyam-sundar.S-k@amd.com, Nehal-bakulchandra.Shah@amd.com,
robh@kernel.org, mchehab+samsung@kernel.org, davem@davemloft.net,
linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org
Subject: Re: [PATCH v9 1/3] dmaengine: ptdma: Initial driver for the AMD PTDMA
Date: Wed, 16 Jun 2021 09:59:32 +0200 [thread overview]
Message-ID: <YMmvZBP9QNc5jf5L@kroah.com> (raw)
In-Reply-To: <YMmt1qhC1dIiYx7O@vkoul-mobl>
On Wed, Jun 16, 2021 at 01:22:54PM +0530, Vinod Koul wrote:
> On 16-06-21, 12:27, Sanjay R Mehta wrote:
> >
> >
> > On 6/16/2021 11:46 AM, Greg KH wrote:
> > > [CAUTION: External Email]
> > >
> > > On Wed, Jun 16, 2021 at 10:24:52AM +0530, Sanjay R Mehta wrote:
> > >>
> > >>
> > >> On 6/16/2021 9:45 AM, Vinod Koul wrote:
> > >>> [CAUTION: External Email]
> > >>>
> > >>> On 15-06-21, 16:50, Sanjay R Mehta wrote:
> > >>>
> > >>>>>> +static struct pt_device *pt_alloc_struct(struct device *dev)
In looking at this, why are you dealing with a "raw" struct device?
Shouldn't this be a parent pointer? Why not pass in the real type that
this can be made a child of?
> > >>>>>> +{
> > >>>>>> + struct pt_device *pt;
> > >>>>>> +
> > >>>>>> + pt = devm_kzalloc(dev, sizeof(*pt), GFP_KERNEL);
> > >>>>>> +
> > >>>>>> + if (!pt)
> > >>>>>> + return NULL;
> > >>>>>> + pt->dev = dev;
> > >>>>>> + pt->ord = atomic_inc_return(&pt_ordinal);
> > >>>>>
> > >>>>> What is the use of this number?
> > >>>>>
> > >>>>
> > >>>> There are eight similar instances of this DMA engine on AMD SOC.
> > >>>> It is to differentiate each of these instances.
> > >>>
> > >>> Are they individual device objects?
> > >>>
> > >>
> > >> Yes, they are individual device objects.
> > >
> > > Then what is "ord" for? Why are you using an atomic variable for this?
> > > What does this field do? Why doesn't the normal way of naming a device
> > > come into play here instead?
> > >
> >
> > Hi Greg,
> >
> > The value of "ord" is incremented for each device instance and then it
> > is used to store different name for each device as shown in below snippet.
> >
> > pt->ord = atomic_inc_return(&pt_ordinal);
> > snprintf(pt->name, MAX_PT_NAME_LEN, "pt-%u", pt->ord);
>
> Okay why not use device->name ?
Ah, I missed this. Yes, do not have 2 names for the same structure,
that is wasteful and confusing.
thanks,
greg k-h
next prev parent reply other threads:[~2021-06-16 7:59 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-02 17:22 [PATCH v9 0/3] Add support for AMD PTDMA controller driver Sanjay R Mehta
2021-06-02 17:22 ` [PATCH v9 1/3] dmaengine: ptdma: Initial driver for the AMD PTDMA Sanjay R Mehta
2021-06-08 17:39 ` Vinod Koul
2021-06-15 11:20 ` Sanjay R Mehta
2021-06-16 4:15 ` Vinod Koul
2021-06-16 4:54 ` Sanjay R Mehta
2021-06-16 6:16 ` Greg KH
2021-06-16 6:57 ` Sanjay R Mehta
2021-06-16 7:17 ` Greg KH
2021-06-16 7:52 ` Vinod Koul
2021-06-16 7:59 ` Greg KH [this message]
2021-06-16 9:46 ` Sanjay R Mehta
2021-06-16 9:56 ` Vinod Koul
2021-06-16 12:00 ` Sanjay R Mehta
2021-06-16 12:23 ` Greg KH
2021-06-16 12:53 ` Sanjay R Mehta
2021-06-16 12:57 ` Greg KH
2021-06-02 17:22 ` [PATCH v9 2/3] dmaengine: ptdma: register PTDMA controller as a DMA resource Sanjay R Mehta
2021-06-08 18:56 ` Vinod Koul
2021-06-15 11:34 ` Sanjay R Mehta
2021-06-16 4:18 ` Vinod Koul
2021-06-16 5:23 ` Sanjay R Mehta
2021-06-20 3:52 ` Sanjay R Mehta
2021-06-02 17:22 ` [PATCH v9 3/3] dmaengine: ptdma: Add debugfs entries for PTDMA Sanjay R Mehta
2021-06-09 14:10 ` Vinod Koul
2021-06-15 11:18 ` Sanjay R Mehta
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