diff mbox series

[net-next,v3,3/9] ravb: Add aligned_tx to struct ravb_hw_info

Message ID 20210818190800.20191-4-biju.das.jz@bp.renesas.com (mailing list archive)
State Accepted
Commit 68ca3c923213b908c14a673f6c3ec808664fae1f
Delegated to: Netdev Maintainers
Headers show
Series Add Gigabit Ethernet driver support | expand

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Commit Message

Biju Das Aug. 18, 2021, 7:07 p.m. UTC 
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@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
v3:
 * New patch
---
 drivers/net/ethernet/renesas/ravb.h      | 1 +
 drivers/net/ethernet/renesas/ravb_main.c | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

Comments

Sergey Shtylyov Aug. 19, 2021, 3:41 p.m. UTC | #1 
On 8/18/21 10:07 PM, Biju Das 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@bp.renesas.com>
> Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> ---
> v3:
>  * New patch

Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>

[...]

MBR, Sergey
Sergey Shtylyov Aug. 19, 2021, 3:43 p.m. UTC | #2 
(Resending from the proper email.)

On 8/18/21 10:07 PM, Biju Das 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@bp.renesas.com>
> Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> ---
> v3:
>  * New patch

Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>

[...]

MBR, Sergey
Geert Uytterhoeven Aug. 23, 2021, 9:14 a.m. UTC | #3 
Hi Biju,

On Wed, Aug 18, 2021 at 9:08 PM Biju Das <biju.das.jz@bp.renesas.com> 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@bp.renesas.com>
> Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

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.

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?

    /*
     * 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
Biju Das Aug. 23, 2021, 9:26 a.m. UTC | #4 
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@bp.renesas.com>
> 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@bp.renesas.com>
> > Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> 
> 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
diff mbox series

Patch

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 6ff0b2626708..4f71e5699ca1 100644
--- 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;
 
 	/* Set function */