Hi Geert,
Thanks for the feedback
> Subject: Re: [PATCH net-next v3 3/9] ravb: Add aligned_tx to struct
> ravb_hw_info
>
> Hi Biju,
>
> On Wed, Aug 18, 2021 at 9:08 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> wrote:
> > R-Car Gen2 needs a 4byte aligned address for the transmission buffer,
> > whereas R-Car Gen3 doesn't have any such restriction.
> >
> > Add aligned_tx to struct ravb_hw_info to select the driver to choose
> > between aligned and unaligned tx buffers.
> >
> > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
>
> Thanks for your patch, which is now commit 68ca3c923213b908 ("ravb:
> Add aligned_tx to struct ravb_hw_info") in net-next.
>
> > --- a/drivers/net/ethernet/renesas/ravb.h
> > +++ b/drivers/net/ethernet/renesas/ravb.h
> > @@ -990,6 +990,7 @@ enum ravb_chip_id {
> >
> > struct ravb_hw_info {
> > enum ravb_chip_id chip_id;
> > + unsigned aligned_tx: 1;
> > };
> >
> > struct ravb_private {
> > diff --git a/drivers/net/ethernet/renesas/ravb_main.c
> > b/drivers/net/ethernet/renesas/ravb_main.c
> > index b6554e5e13af..dbccf2cd89b2 100644
> > --- a/drivers/net/ethernet/renesas/ravb_main.c
> > +++ b/drivers/net/ethernet/renesas/ravb_main.c
> > @@ -1930,6 +1930,7 @@ static const struct ravb_hw_info
> > ravb_gen3_hw_info = {
> >
> > static const struct ravb_hw_info ravb_gen2_hw_info = {
> > .chip_id = RCAR_GEN2,
> > + .aligned_tx = 1,
> > };
> >
> > static const struct of_device_id ravb_match_table[] = { @@ -2140,7
> > +2141,7 @@ static int ravb_probe(struct platform_device *pdev)
> > ndev->max_mtu = 2048 - (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN);
> > ndev->min_mtu = ETH_MIN_MTU;
> >
> > - priv->num_tx_desc = info->chip_id == RCAR_GEN2 ?
> > + priv->num_tx_desc = info->aligned_tx ?
> > NUM_TX_DESC_GEN2 : NUM_TX_DESC_GEN3;
>
> At first look, this change does not seem to match the patch description.
> Upon a deeper look, it is correct, as num_tx_desc is also used to control
> alignment.
This changes introduced by the commit [1], where it used num_tx_desc related to 4byte alignment restriction.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/net/ethernet/renesas/ravb_main.c?h=v5.14-rc7&id=f543305da9b5a5efaf6fa61606e8bbc8977f406d
>
> But now NUM_TX_DESC_GEN[23] no longer match their use.
> Perhaps they should be renamed, or replaced by hardcoded values, with a
> comment?
OK, will replace this macros with hardcoded values with a comment.
Regards,
Biju
>
> /*
> * FIXME: Explain the relationship between alignment and number of
> buffers
> */
> priv->num_tx_desc = info->aligned_tx ? 2 : 1;
>
> >
> > /* Set function */
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
> m68k.org
>
> In personal conversations with technical people, I call myself a hacker.
> But when I'm talking to journalists I just say "programmer" or something
> like that.
> -- Linus Torvalds
