linux-kernel - Re: [PATCH 10/11] net: macb: Add support for RP1's MACB variant

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Message-ID: <c0b904d8-073d-47ec-9466-28ae3a212dac@broadcom.com>
Date: Wed, 21 Aug 2024 10:01:26 -0700
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Andrea della Porta <andrea.porta@...e.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>,
 Linus Walleij <linus.walleij@...aro.org>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 Derek Kiernan <derek.kiernan@....com>, Dragan Cvetic
 <dragan.cvetic@....com>, Arnd Bergmann <arnd@...db.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Nicolas Ferre <nicolas.ferre@...rochip.com>,
 Claudiu Beznea <claudiu.beznea@...on.dev>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Saravana Kannan <saravanak@...gle.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
 linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
 linux-rpi-kernel@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
 netdev@...r.kernel.org, linux-pci@...r.kernel.org,
 linux-arch@...r.kernel.org, Lee Jones <lee@...nel.org>,
 Andrew Lunn <andrew@...n.ch>, Stefan Wahren <wahrenst@....net>
Subject: Re: [PATCH 10/11] net: macb: Add support for RP1's MACB variant

On 8/20/24 07:36, Andrea della Porta wrote:
> RaspberryPi RP1 contains Cadence's MACB core. Implement the
> changes to be able to operate the customization in the RP1.
> 
> Signed-off-by: Andrea della Porta <andrea.porta@...e.com>

You are doing a lot of things, all at once, and you should consider 
extracting your change into a smaller subset with bug fixes first:

- one commit which writes to the RBQPH the upper 32-bits of the RX ring 
DMA address, that looks like a bug fix

- one commit which retriggers a buffer read, even though that appears to 
be RP1 specific maybe, if not, then this is also a bug fix

- one commit that adds support for macb_shutdown() to kill DMA operations

- one commit which adds support for a configurable PHY reset line + 
delay specified in milli seconds

- one commit which adds support for controling the interrupt coalescing 
settings

And then you can add all of the RP1 specific bits like the AXI bridge 
configuration.

[snip]

> @@ -1228,6 +1246,7 @@ struct macb_queue {
>   	dma_addr_t		tx_ring_dma;
>   	struct work_struct	tx_error_task;
>   	bool			txubr_pending;
> +	bool			tx_pending;
>   	struct napi_struct	napi_tx;
>   
>   	dma_addr_t		rx_ring_dma;
> @@ -1293,9 +1312,15 @@ struct macb {
>   
>   	u32			caps;
>   	unsigned int		dma_burst_length;
> +	u8			aw2w_max_pipe;
> +	u8			ar2r_max_pipe;
> +	bool			use_aw2b_fill;
>   
>   	phy_interface_t		phy_interface;
>   
> +	struct gpio_desc	*phy_reset_gpio;
> +	int			phy_reset_ms;

The delay cannot be negative, so this needs to be unsigned int.

> +
>   	/* AT91RM9200 transmit queue (1 on wire + 1 queued) */
>   	struct macb_tx_skb	rm9200_txq[2];
>   	unsigned int		max_tx_length;
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 11665be3a22c..5eb5be6c96fc 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -41,6 +41,9 @@
>   #include <linux/inetdevice.h>
>   #include "macb.h"
>   
> +static unsigned int txdelay = 35;
> +module_param(txdelay, uint, 0644);
> +
>   /* This structure is only used for MACB on SiFive FU540 devices */
>   struct sifive_fu540_macb_mgmt {
>   	void __iomem *reg;
> @@ -334,7 +337,7 @@ static int macb_mdio_wait_for_idle(struct macb *bp)
>   	u32 val;
>   
>   	return readx_poll_timeout(MACB_READ_NSR, bp, val, val & MACB_BIT(IDLE),
> -				  1, MACB_MDIO_TIMEOUT);
> +				  100, MACB_MDIO_TIMEOUT);

Why do we need to increase how frequently we poll?
-- 
Florian