netdev - Re: [net PATCH 2/6] fbnic: Gate AXI read/write enabling on FW mailbox

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Message-ID: <20250502105038.GJ3339421@horms.kernel.org>
Date: Fri, 2 May 2025 11:50:38 +0100
From: Simon Horman <horms@...nel.org>
To: Alexander Duyck <alexander.duyck@...il.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
	pabeni@...hat.com
Subject: Re: [net PATCH 2/6] fbnic: Gate AXI read/write enabling on FW mailbox

On Thu, May 01, 2025 at 04:30:03PM -0700, Alexander Duyck wrote:
> From: Alexander Duyck <alexanderduyck@...com>
> 
> In order to prevent the device from throwing spurious writes and/or reads
> at us we need to gate the AXI fabric interface to the PCIe until such time
> as we know the FW is in a known good state.
> 
> To accomplish this we use the mailbox as a mechanism for us to recognize
> that the FW has acknowledged our presence and is no longer sending any
> stale message data to us.
> 
> We start in fbnic_mbx_init by calling fbnic_mbx_reset_desc_ring function,
> disabling the DMA in both directions, and then invalidating all the
> descriptors in each ring.
> 
> We then poll the mailbox in fbnic_mbx_poll_tx_ready and when the interrupt
> is set by the FW we pick it up and mark the mailboxes as ready, while also
> enabling the DMA.
> 
> Once we have completed all the transactions and need to shut down we call
> into fbnic_mbx_clean which will in turn call fbnic_mbx_reset_desc_ring for
> each ring and shut down the DMA and once again invalidate the descriptors.
> 
> Fixes: 3646153161f1 ("eth: fbnic: Add register init to set PCIe/Ethernet device config")
> Fixes: da3cde08209e ("eth: fbnic: Add FW communication mechanism")

nit: No blank linke here please.

> Signed-off-by: Alexander Duyck <alexanderduyck@...com>

The nit above aside, this looks good to me.

Reviewed-by: Simon Horman <horms@...nel.org>

...