linux-kernel - Re: [PATCH v3 fwctl 4/5] fwctl/bnxt

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Message-ID: <CACDg6nVDh4MXwnNzo5H5MfZ7-NeJ4c2J3SmFw9wZub_nEvbgpA@mail.gmail.com>
Date: Thu, 5 Feb 2026 12:47:53 -0500
From: Andy Gospodarek <andrew.gospodarek@...adcom.com>
To: Jason Gunthorpe <jgg@...pe.ca>
Cc: Pavan Chebbi <pavan.chebbi@...adcom.com>, Saeed Mahameed <saeedm@...dia.com>, 
	michael.chan@...adcom.com, linux-kernel@...r.kernel.org, dave.jiang@...el.com, 
	Jonathan.Cameron@...wei.com, gospo@...adcom.com, selvin.xavier@...adcom.com, 
	leon@...nel.org, kalesh-anakkur.purayil@...adcom.com
Subject: Re: [PATCH v3 fwctl 4/5] fwctl/bnxt_fwctl: Add bnxt fwctl device

On Thu, Feb 5, 2026 at 12:33 PM Jason Gunthorpe <jgg@...pe.ca> wrote:
>
> On Thu, Feb 05, 2026 at 09:55:08AM +0530, Pavan Chebbi wrote:
> > >
> > > I find it a bit weird that the user needs to provide dma information
and
> > > structure ! this is supposed to be completely hidden by the driver to
> > > simplify user space, the driver handles dma and access to HW, user
space
> > > just provides the commands and payloads and driver carries the
input/output
> > > for that user space.
> >
> > This is so because our FW commands require optional DMA-able buffers.
> > The application is only giving us the information that the driver
> > should encapsulate in additional DMA-able buffers.
> > There is a defined format for exchange of this information, because
> > every command has a different number of additional buffers. Also the
> > majority of the commands don't need any additional buffers.
> > I hope this answers your next comments also.
>
> Now I have questions, who allocates these buffers, how do they get DMA
> mapped, who does all the copying??
>

Jason, this is all done in bnxtctl_fw_rpc() and the functions it calls in
this (or the v4 version) of this patch.

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