| Message ID | 20201218173843.141046-1-f.fainelli@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net] net: systemport: set dev->max_mtu to UMAC_MAX_MTU_SIZE | expand |
On Fri, Dec 18, 2020 at 12:30:20PM -0800, Florian Fainelli wrote: > On 12/18/20 12:24 PM, Vladimir Oltean wrote: > > Hi Florian, > > > > On Fri, Dec 18, 2020 at 09:38:43AM -0800, Florian Fainelli wrote: > >> The driver is already allocating receive buffers of 2KiB and the > >> Ethernet MAC is configured to accept frames up to UMAC_MAX_MTU_SIZE. > >> > >> Fixes: bfcb813203e6 ("net: dsa: configure the MTU for switch ports") > >> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> > >> --- > >> drivers/net/ethernet/broadcom/bcmsysport.c | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c > >> index 0fdd19d99d99..b1ae9eb8f247 100644 > >> --- a/drivers/net/ethernet/broadcom/bcmsysport.c > >> +++ b/drivers/net/ethernet/broadcom/bcmsysport.c > >> @@ -2577,6 +2577,7 @@ static int bcm_sysport_probe(struct platform_device *pdev) > >> NETIF_F_HW_VLAN_CTAG_TX; > >> dev->hw_features |= dev->features; > >> dev->vlan_features |= dev->features; > >> + dev->max_mtu = UMAC_MAX_MTU_SIZE; > >> > >> /* Request the WOL interrupt and advertise suspend if available */ > >> priv->wol_irq_disabled = 1; > >> -- > >> 2.25.1 > >> > > > > Do you want to treat the SYSTEMPORT Lite differently? > > > > /* Set maximum frame length */ > > if (!priv->is_lite) > > umac_writel(priv, UMAC_MAX_MTU_SIZE, UMAC_MAX_FRAME_LEN); > > else > > gib_set_pad_extension(priv); > > SYSTEMPORT Lite does not actually validate the frame length, so setting > a maximum number to the buffer size we allocate could work, but I don't > see a reason to differentiate the two types of MACs here. And if the Lite doesn't validate the frame length, then shouldn't it report a max_mtu equal to the max_mtu of the attached DSA switch, plus the Broadcom tag length? Doesn't the b53 driver support jumbo frames?
On Fri, Dec 18, 2020 at 01:08:58PM -0800, Florian Fainelli wrote: > On 12/18/20 1:02 PM, Vladimir Oltean wrote: > > On Fri, Dec 18, 2020 at 12:54:33PM -0800, Florian Fainelli wrote: > >> On 12/18/20 12:52 PM, Vladimir Oltean wrote: > >>> On Fri, Dec 18, 2020 at 12:30:20PM -0800, Florian Fainelli wrote: > >>>> On 12/18/20 12:24 PM, Vladimir Oltean wrote: > >>>>> Hi Florian, > >>>>> > >>>>> On Fri, Dec 18, 2020 at 09:38:43AM -0800, Florian Fainelli wrote: > >>>>>> The driver is already allocating receive buffers of 2KiB and the > >>>>>> Ethernet MAC is configured to accept frames up to UMAC_MAX_MTU_SIZE. > >>>>>> > >>>>>> Fixes: bfcb813203e6 ("net: dsa: configure the MTU for switch ports") > >>>>>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> > >>>>>> --- > >>>>>> drivers/net/ethernet/broadcom/bcmsysport.c | 1 + > >>>>>> 1 file changed, 1 insertion(+) > >>>>>> > >>>>>> diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c > >>>>>> index 0fdd19d99d99..b1ae9eb8f247 100644 > >>>>>> --- a/drivers/net/ethernet/broadcom/bcmsysport.c > >>>>>> +++ b/drivers/net/ethernet/broadcom/bcmsysport.c > >>>>>> @@ -2577,6 +2577,7 @@ static int bcm_sysport_probe(struct platform_device *pdev) > >>>>>> NETIF_F_HW_VLAN_CTAG_TX; > >>>>>> dev->hw_features |= dev->features; > >>>>>> dev->vlan_features |= dev->features; > >>>>>> + dev->max_mtu = UMAC_MAX_MTU_SIZE; > >>>>>> > >>>>>> /* Request the WOL interrupt and advertise suspend if available */ > >>>>>> priv->wol_irq_disabled = 1; > >>>>>> -- > >>>>>> 2.25.1 > >>>>>> > >>>>> > >>>>> Do you want to treat the SYSTEMPORT Lite differently? > >>>>> > >>>>> /* Set maximum frame length */ > >>>>> if (!priv->is_lite) > >>>>> umac_writel(priv, UMAC_MAX_MTU_SIZE, UMAC_MAX_FRAME_LEN); > >>>>> else > >>>>> gib_set_pad_extension(priv); > >>>> > >>>> SYSTEMPORT Lite does not actually validate the frame length, so setting > >>>> a maximum number to the buffer size we allocate could work, but I don't > >>>> see a reason to differentiate the two types of MACs here. > >>> > >>> And if the Lite doesn't validate the frame length, then shouldn't it > >>> report a max_mtu equal to the max_mtu of the attached DSA switch, plus > >>> the Broadcom tag length? Doesn't the b53 driver support jumbo frames? > >> > >> And how would I do that without create a horrible layering violation in > >> either the systemport driver or DSA? Yes the b53 driver supports jumbo > >> frames. > > > > Sorry, I don't understand where is the layering violation (maybe it doesn't > > help me either that I'm not familiar with Broadcom architectures). > > > > Is the SYSTEMPORT Lite always used as a DSA master, or could it also be > > used standalone? What would be the issue with hardcoding a max_mtu value > > which is large enough for b53 to use jumbo frames? > > SYSTEMPORT Lite is always used as a DSA master AFAICT given its GMII > Integration Block (GIB) was specifically designed with another MAC and > particularly that of a switch on the other side. > > The layering violation I am concerned with is that we do not know ahead > of time which b53 switch we are going to be interfaced with, and they > have various limitations on the sizes they support. Right now b53 only > concerns itself with returning JMS_MAX_SIZE, but I am fairly positive > this needs fixing given the existing switches supported by the driver. Maybe we don't need to over-engineer this. As long as you report a large enough max_mtu in the SYSTEMPORT Lite driver to accomodate for all possible revisions of embedded switches, and the max_mtu of the switch itself is still accurate and representative of the switch revision limits, I think that's good enough.
On 12/18/2020 1:17 PM, Florian Fainelli wrote: >>>>>>> SYSTEMPORT Lite does not actually validate the frame length, so setting >>>>>>> a maximum number to the buffer size we allocate could work, but I don't >>>>>>> see a reason to differentiate the two types of MACs here. >>>>>> >>>>>> And if the Lite doesn't validate the frame length, then shouldn't it >>>>>> report a max_mtu equal to the max_mtu of the attached DSA switch, plus >>>>>> the Broadcom tag length? Doesn't the b53 driver support jumbo frames? >>>>> >>>>> And how would I do that without create a horrible layering violation in >>>>> either the systemport driver or DSA? Yes the b53 driver supports jumbo >>>>> frames. >>>> >>>> Sorry, I don't understand where is the layering violation (maybe it doesn't >>>> help me either that I'm not familiar with Broadcom architectures). >>>> >>>> Is the SYSTEMPORT Lite always used as a DSA master, or could it also be >>>> used standalone? What would be the issue with hardcoding a max_mtu value >>>> which is large enough for b53 to use jumbo frames? >>> >>> SYSTEMPORT Lite is always used as a DSA master AFAICT given its GMII >>> Integration Block (GIB) was specifically designed with another MAC and >>> particularly that of a switch on the other side. >>> >>> The layering violation I am concerned with is that we do not know ahead >>> of time which b53 switch we are going to be interfaced with, and they >>> have various limitations on the sizes they support. Right now b53 only >>> concerns itself with returning JMS_MAX_SIZE, but I am fairly positive >>> this needs fixing given the existing switches supported by the driver. >> >> Maybe we don't need to over-engineer this. As long as you report a large >> enough max_mtu in the SYSTEMPORT Lite driver to accomodate for all >> possible revisions of embedded switches, and the max_mtu of the switch >> itself is still accurate and representative of the switch revision limits, >> I think that's good enough. > > I suppose that is fair, v2 coming, thanks! I was going to issue a v2 for this patch, but given that we don't allocate buffers larger than 2KiB and there is really no need to implement ndo_change_mtu(), is there really a point not to use UMAC_MAX_MTU_SIZE for both variants of the SYSTEMPORT MAC? -- Florian
On Mon, Dec 21, 2020 at 01:49:03PM -0800, Florian Fainelli wrote: > On 12/18/2020 1:17 PM, Florian Fainelli wrote: > >>>>>>> SYSTEMPORT Lite does not actually validate the frame length, so setting > >>>>>>> a maximum number to the buffer size we allocate could work, but I don't > >>>>>>> see a reason to differentiate the two types of MACs here. > >>>>>> > >>>>>> And if the Lite doesn't validate the frame length, then shouldn't it > >>>>>> report a max_mtu equal to the max_mtu of the attached DSA switch, plus > >>>>>> the Broadcom tag length? Doesn't the b53 driver support jumbo frames? > >>>>> > >>>>> And how would I do that without create a horrible layering violation in > >>>>> either the systemport driver or DSA? Yes the b53 driver supports jumbo > >>>>> frames. > >>>> > >>>> Sorry, I don't understand where is the layering violation (maybe it doesn't > >>>> help me either that I'm not familiar with Broadcom architectures). > >>>> > >>>> Is the SYSTEMPORT Lite always used as a DSA master, or could it also be > >>>> used standalone? What would be the issue with hardcoding a max_mtu value > >>>> which is large enough for b53 to use jumbo frames? > >>> > >>> SYSTEMPORT Lite is always used as a DSA master AFAICT given its GMII > >>> Integration Block (GIB) was specifically designed with another MAC and > >>> particularly that of a switch on the other side. > >>> > >>> The layering violation I am concerned with is that we do not know ahead > >>> of time which b53 switch we are going to be interfaced with, and they > >>> have various limitations on the sizes they support. Right now b53 only > >>> concerns itself with returning JMS_MAX_SIZE, but I am fairly positive > >>> this needs fixing given the existing switches supported by the driver. > >> > >> Maybe we don't need to over-engineer this. As long as you report a large > >> enough max_mtu in the SYSTEMPORT Lite driver to accomodate for all > >> possible revisions of embedded switches, and the max_mtu of the switch > >> itself is still accurate and representative of the switch revision limits, > >> I think that's good enough. > > > > I suppose that is fair, v2 coming, thanks! > > I was going to issue a v2 for this patch, but given that we don't > allocate buffers larger than 2KiB and there is really no need to > implement ndo_change_mtu(), is there really a point not to use > UMAC_MAX_MTU_SIZE for both variants of the SYSTEMPORT MAC? After your first reply that "the Lite doesn't validate the frame length", I was under the impression that it is sufficient to declare a larger max_mtu such as JMS_MAX_SIZE and 9K jumbo frames would just work. But with the current buffer allocation in bcm_sysport_rx_refill it clearly wouldn't. A stupid confusion really. So yeah, sorry for having you resend a v2 with no change. If it helps you could add to the patch: Reviewed-by: Vladimir Oltean <olteanv@gmail.com> Thanks again for explaining.
On 12/21/2020 2:25 PM, Vladimir Oltean wrote: > On Mon, Dec 21, 2020 at 01:49:03PM -0800, Florian Fainelli wrote: >> On 12/18/2020 1:17 PM, Florian Fainelli wrote: >>>>>>>>> SYSTEMPORT Lite does not actually validate the frame length, so setting >>>>>>>>> a maximum number to the buffer size we allocate could work, but I don't >>>>>>>>> see a reason to differentiate the two types of MACs here. >>>>>>>> >>>>>>>> And if the Lite doesn't validate the frame length, then shouldn't it >>>>>>>> report a max_mtu equal to the max_mtu of the attached DSA switch, plus >>>>>>>> the Broadcom tag length? Doesn't the b53 driver support jumbo frames? >>>>>>> >>>>>>> And how would I do that without create a horrible layering violation in >>>>>>> either the systemport driver or DSA? Yes the b53 driver supports jumbo >>>>>>> frames. >>>>>> >>>>>> Sorry, I don't understand where is the layering violation (maybe it doesn't >>>>>> help me either that I'm not familiar with Broadcom architectures). >>>>>> >>>>>> Is the SYSTEMPORT Lite always used as a DSA master, or could it also be >>>>>> used standalone? What would be the issue with hardcoding a max_mtu value >>>>>> which is large enough for b53 to use jumbo frames? >>>>> >>>>> SYSTEMPORT Lite is always used as a DSA master AFAICT given its GMII >>>>> Integration Block (GIB) was specifically designed with another MAC and >>>>> particularly that of a switch on the other side. >>>>> >>>>> The layering violation I am concerned with is that we do not know ahead >>>>> of time which b53 switch we are going to be interfaced with, and they >>>>> have various limitations on the sizes they support. Right now b53 only >>>>> concerns itself with returning JMS_MAX_SIZE, but I am fairly positive >>>>> this needs fixing given the existing switches supported by the driver. >>>> >>>> Maybe we don't need to over-engineer this. As long as you report a large >>>> enough max_mtu in the SYSTEMPORT Lite driver to accomodate for all >>>> possible revisions of embedded switches, and the max_mtu of the switch >>>> itself is still accurate and representative of the switch revision limits, >>>> I think that's good enough. >>> >>> I suppose that is fair, v2 coming, thanks! >> >> I was going to issue a v2 for this patch, but given that we don't >> allocate buffers larger than 2KiB and there is really no need to >> implement ndo_change_mtu(), is there really a point not to use >> UMAC_MAX_MTU_SIZE for both variants of the SYSTEMPORT MAC? > > After your first reply that "the Lite doesn't validate the frame length", I was > under the impression that it is sufficient to declare a larger max_mtu such as > JMS_MAX_SIZE and 9K jumbo frames would just work. But with the current buffer > allocation in bcm_sysport_rx_refill it clearly wouldn't. A stupid confusion > really. So yeah, sorry for having you resend a v2 with no change. > If it helps you could add to the patch: > > Reviewed-by: Vladimir Oltean <olteanv@gmail.com> > > Thanks again for explaining. No worries, Jakub, David, do you need me to resend or can you pick it up from patchwork? -- Florian
diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c index 0fdd19d99d99..b1ae9eb8f247 100644 --- a/drivers/net/ethernet/broadcom/bcmsysport.c +++ b/drivers/net/ethernet/broadcom/bcmsysport.c @@ -2577,6 +2577,7 @@ static int bcm_sysport_probe(struct platform_device *pdev) NETIF_F_HW_VLAN_CTAG_TX; dev->hw_features |= dev->features; dev->vlan_features |= dev->features; + dev->max_mtu = UMAC_MAX_MTU_SIZE; /* Request the WOL interrupt and advertise suspend if available */ priv->wol_irq_disabled = 1;
The driver is already allocating receive buffers of 2KiB and the Ethernet MAC is configured to accept frames up to UMAC_MAX_MTU_SIZE. Fixes: bfcb813203e6 ("net: dsa: configure the MTU for switch ports") Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> --- drivers/net/ethernet/broadcom/bcmsysport.c | 1 + 1 file changed, 1 insertion(+)