Messages in this thread | | | Subject | Re: [PATCH net v3] net: macb: remove change_mtu callback | From | Thomas Perrot <> | Date | Wed, 13 Mar 2024 14:39:05 +0100 |
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Hello,
On Mon, 2024-03-11 at 16:17 -0700, Jakub Kicinski wrote: > On Mon, 11 Mar 2024 16:43:15 +0100 thomas.perrot@bootlin.com wrote: > > Because it doesn't allow MTU changes when the interface is up, > > although > > it is not necessary. > > > > This callback has been added to add in a first implementation of > > the Jumbo > > support [1],since it has been reworked and moved to the probe [2]. > > > > With this patch the core will set the MTU, regardless of if the > > interface > > is up or not. > > > > [1] commit a5898ea09aad ("net: macb: Add change_mtu callback with > > jumbo support") > > [2] commit 44770e1180de ("ethernet: use core min/max MTU checking") > > > > Fixes: 44770e1180de ("ethernet: use core min/max MTU checking") > > static void macb_init_rx_buffer_size(struct macb *bp, size_t size) > { > if (!macb_is_gem(bp)) { > bp->rx_buffer_size = MACB_RX_BUFFER_SIZE; > } else { > bp->rx_buffer_size = size; > > where size is: > > size_t bufsz = dev->mtu + ETH_HLEN + ETH_FCS_LEN + > NET_IP_ALIGN; > > I guess you tested this on a platform where !macb_is_gem(bp) ?
Thank you for your review, indeed that won’t be correct on GEM in when the MTU used to initialize the RX buffer is lower than the new MTU.
So, I will suggest another patch with an acceptable solution.
Kind regards, Thomas Perrot
> Otherwise the buffer size seems to be based on MTU and the proposed > change won't be correct.
-- Thomas Perrot, Bootlin Embedded Linux and kernel engineering https://bootlin.com
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