netdev - RE: [PATCH V4 net 5/5] net: stmmac: re-init rx buffers when mac resume back

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Date:   Tue, 23 Feb 2021 07:16:52 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     Jakub Kicinski <kuba@...nel.org>
CC:     "peppe.cavallaro@...com" <peppe.cavallaro@...com>,
        "alexandre.torgue@...com" <alexandre.torgue@...com>,
        "joabreu@...opsys.com" <joabreu@...opsys.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V4 net 5/5] net: stmmac: re-init rx buffers when mac
 resume back


> -----Original Message-----
> From: Jakub Kicinski <kuba@...nel.org>
> Sent: 2021年2月23日 3:48
> To: Joakim Zhang <qiangqing.zhang@....com>
> Cc: peppe.cavallaro@...com; alexandre.torgue@...com;
> joabreu@...opsys.com; davem@...emloft.net; netdev@...r.kernel.org;
> dl-linux-imx <linux-imx@....com>
> Subject: Re: [PATCH V4 net 5/5] net: stmmac: re-init rx buffers when mac
> resume back
> 
> On Sat, 20 Feb 2021 07:52:46 +0000 Joakim Zhang wrote:
> > > I'm not sure why you recycle and reallocate every buffer. Isn't it
> > > enough to reinitialize the descriptors with the buffers which are already
> allocated?
> >
> > As I know, the receive buffer address is not fixed after allocated, it
> > will recycle and re-allocate in stmmac_rx(), where to handle the
> > receive buffers.
> 
> Not sure what you mean by that. The driver must know the addresses of the
> memory it allocated and handed over to the device.

What I mean is that, in stmmac driver, it creates a page pool for rx patch, it will always recycle and re-allocate pages to fill descriptors' dma address.

Best Regards,
Joakim Zhang
> > It should be enough to re-initialize the descriptors with the buffers
> > if it is possible. Could you point me how to do it?