RE: [PATCH net] net: lan743x: Add set RFE read fifo threshold for PCI1x1x chips

Raju.Lakkaraju
2024-03-18T06:50:34Z

Hi Simon Horman,

Thank you for review comments.

> -----Original Message-----
> From: Simon Horman <horms@kernel.org>
> Sent: Saturday, March 9, 2024 12:58 AM
> To: Raju Lakkaraju - I30499 <Raju.Lakkaraju@microchip.com>
> Cc: netdev@vger.kernel.org; davem@davemloft.net; kuba@kernel.org;
> pabeni@redhat.com; edumazet@google.com; linux-kernel@vger.kernel.org;
> Bryan Whitehead - C21958 <Bryan.Whitehead@microchip.com>;
> UNGLinuxDriver <UNGLinuxDriver@microchip.com>
> Subject: Re: [PATCH net] net: lan743x: Add set RFE read fifo threshold for
> PCI1x1x chips
>
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
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>
> On Thu, Mar 07, 2024 at 02:28:23PM +0530, Raju Lakkaraju wrote:
> > The RFE (Receive Filtering Engine) read fifo threshold hardware
> > default should be overwritten to 3 for PCI1x1x Rev B0 devices to
> > prevent lockup during some stress tests using frames that include VLAN
> tags.
> > Rev C0 and later hardware already defaults to 3.
> >
> > Fixes: bb4f6bffe33c ("net: lan743x: Add PCI11010 / PCI11414 device
> > IDs")
> > Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microchip.com>
> > ---
> > drivers/net/ethernet/microchip/lan743x_main.c | 17 +++++++++++++++++
> > drivers/net/ethernet/microchip/lan743x_main.h | 5 +++++
> > 2 files changed, 22 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/microchip/lan743x_main.c
> > b/drivers/net/ethernet/microchip/lan743x_main.c
> > index 45e209a7d083..aec2d100ab87 100644
> > --- a/drivers/net/ethernet/microchip/lan743x_main.c
> > +++ b/drivers/net/ethernet/microchip/lan743x_main.c
> > @@ -3272,6 +3272,22 @@ static void lan743x_full_cleanup(struct
> lan743x_adapter *adapter)
> > lan743x_pci_cleanup(adapter);
> > }
> >
> > +static int pci11x1x_set_rfe_rd_fifo_threshold(struct lan743x_adapter
> > +*adapter) {
> > + u16 rev = adapter->csr.id_rev & ID_REV_CHIP_REV_MASK_;
> > +
> > + if (rev == ID_REV_CHIP_REV_PCI11X1X_B0_) {
> > + int misc_ctl;
> > +
> > + misc_ctl = lan743x_csr_read(adapter, MISC_CTL_0);
> > + misc_ctl &= ~MISC_CTL_0_RFE_READ_FIFO_MASK_;
> > + misc_ctl |= (0x3 << MISC_CTL_0_RFE_READ_FIFO_SHIFT_);
> > + lan743x_csr_write(adapter, MISC_CTL_0, misc_ctl);
>
> Hi Raju,
>
> Some minor nits from my side:
>
> - misc_ctl could be an unsigned integer

Ok.

> - The above could probably use FIELD_PREP, which in turn
> probably means that MISC_CTL_0_RFE_READ_FIFO_SHIFT_ isn't needed

Ok. I will change

> - 0x3 could be a #define - what does it mean?
0x3 is empirical value of "Receive Filtering Engine read fifo threshold" hardware value for PCI11X1X Rev B0 chips
I will add the same comment there.

>
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static int lan743x_hardware_init(struct lan743x_adapter *adapter,
> > struct pci_dev *pdev) {
>
> ...

Thanks,
Raju