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

[Simon Horman <horms@kernel.org>]

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
- The above could probably use FIELD_PREP, which in turn
  probably means that MISC_CTL_0_RFE_READ_FIFO_SHIFT_ isn't needed
- 0x3 could be a #define - what does it mean?

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

...