linux-kernel - Re: [PATCH net-next 14/15] net: sparx5: add compatible strings for lan969x and verify the target

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Message-ID: <cetor3ohhg6rzf3w2cm6hqxsqukh52nm54mp7tizb2qc3x44j4@n53v6btq6t6r>
Date: Wed, 23 Oct 2024 10:14:54 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Daniel Machon <daniel.machon@...rochip.com>
Cc: "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, andrew@...n.ch, Lars Povlsen <lars.povlsen@...rochip.com>, 
	Steen Hegelund <Steen.Hegelund@...rochip.com>, horatiu.vultur@...rochip.com, 
	jensemil.schulzostergaard@...rochip.com, Parthiban.Veerasooran@...rochip.com, 
	Raju.Lakkaraju@...rochip.com, UNGLinuxDriver@...rochip.com, 
	Richard Cochran <richardcochran@...il.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, jacob.e.keller@...el.com, 
	ast@...erby.net, maxime.chevallier@...tlin.com, netdev@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH net-next 14/15] net: sparx5: add compatible strings for
 lan969x and verify the target

On Mon, Oct 21, 2024 at 03:58:51PM +0200, Daniel Machon wrote:
> Add compatible strings for the twelve lan969x SKU's (Stock Keeping Unit)
> that we support, and verify that the devicetree target is supported by
> the chip target.
> 
> Each SKU supports different bandwidths and features (see [1] for
> details). We want to be able to run a SKU with a lower bandwidth and/or
> feature set, than what is supported by the actual chip. In order to
> accomplish this we:
> 
>     - add new field sparx5->target_dt that reflects the target from the
>       devicetree (compatible string).
> 
>     - compare the devicetree target with the actual chip target. If the
>       bandwidth and features provided by the devicetree target is
>       supported by the chip, we approve - otherwise reject.
> 
>     - set the core clock and features based on the devicetree target
> 
> [1] https://www.microchip.com/en-us/product/lan9698
> 
> Reviewed-by: Steen Hegelund <Steen.Hegelund@...rochip.com>
> Signed-off-by: Daniel Machon <daniel.machon@...rochip.com>
> ---
>  drivers/net/ethernet/microchip/sparx5/Makefile     |   1 +
>  .../net/ethernet/microchip/sparx5/sparx5_main.c    | 194 ++++++++++++++++++++-
>  .../net/ethernet/microchip/sparx5/sparx5_main.h    |   1 +
>  3 files changed, 193 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microchip/sparx5/Makefile b/drivers/net/ethernet/microchip/sparx5/Makefile
> index 3435ca86dd70..8fe302415563 100644
> --- a/drivers/net/ethernet/microchip/sparx5/Makefile
> +++ b/drivers/net/ethernet/microchip/sparx5/Makefile
> @@ -19,3 +19,4 @@ sparx5-switch-$(CONFIG_DEBUG_FS) += sparx5_vcap_debugfs.o
>  # Provide include files
>  ccflags-y += -I$(srctree)/drivers/net/ethernet/microchip/vcap
>  ccflags-y += -I$(srctree)/drivers/net/ethernet/microchip/fdma
> +ccflags-y += -I$(srctree)/drivers/net/ethernet/microchip/lan969x
> diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_main.c b/drivers/net/ethernet/microchip/sparx5/sparx5_main.c
> index 5c986c373b3e..edbe639d98c5 100644
> --- a/drivers/net/ethernet/microchip/sparx5/sparx5_main.c
> +++ b/drivers/net/ethernet/microchip/sparx5/sparx5_main.c
> @@ -24,6 +24,8 @@
>  #include <linux/types.h>
>  #include <linux/reset.h>
>  
> +#include "lan969x.h" /* lan969x_desc */
> +
>  #include "sparx5_main_regs.h"
>  #include "sparx5_main.h"
>  #include "sparx5_port.h"
> @@ -227,6 +229,168 @@ bool is_sparx5(struct sparx5 *sparx5)
>  	}
>  }
>  
> +/* Set the devicetree target based on the compatible string */
> +static int sparx5_set_target_dt(struct sparx5 *sparx5)
> +{
> +	struct device_node *node = sparx5->pdev->dev.of_node;
> +
> +	if (is_sparx5(sparx5))
> +		/* For Sparx5 the devicetree target is always the chip target */
> +		sparx5->target_dt = sparx5->target_ct;
> +	else if (of_device_is_compatible(node, "microchip,lan9691-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9691VAO;
> +	else if (of_device_is_compatible(node, "microchip,lan9692-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9692VAO;
> +	else if (of_device_is_compatible(node, "microchip,lan9693-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9693VAO;
> +	else if (of_device_is_compatible(node, "microchip,lan9694-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9694;
> +	else if (of_device_is_compatible(node, "microchip,lan9695-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9694TSN;
> +	else if (of_device_is_compatible(node, "microchip,lan9696-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9696;
> +	else if (of_device_is_compatible(node, "microchip,lan9697-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9696TSN;
> +	else if (of_device_is_compatible(node, "microchip,lan9698-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9698;
> +	else if (of_device_is_compatible(node, "microchip,lan9699-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9698TSN;
> +	else if (of_device_is_compatible(node, "microchip,lan969a-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9694RED;
> +	else if (of_device_is_compatible(node, "microchip,lan969b-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9696RED;
> +	else if (of_device_is_compatible(node, "microchip,lan969c-switch"))
> +		sparx5->target_dt = SPX5_TARGET_CT_LAN9698RED;
> +	else
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +/* Compare the devicetree target with the chip target.
> + * Make sure the chip target supports the features and bandwidth requested
> + * from the devicetree target.
> + */
> +static int sparx5_verify_target(struct sparx5 *sparx5)
> +{
> +	switch (sparx5->target_dt) {
> +	case SPX5_TARGET_CT_7546:
> +	case SPX5_TARGET_CT_7549:
> +	case SPX5_TARGET_CT_7552:
> +	case SPX5_TARGET_CT_7556:
> +	case SPX5_TARGET_CT_7558:
> +	case SPX5_TARGET_CT_7546TSN:
> +	case SPX5_TARGET_CT_7549TSN:
> +	case SPX5_TARGET_CT_7552TSN:
> +	case SPX5_TARGET_CT_7556TSN:
> +	case SPX5_TARGET_CT_7558TSN:
> +		return 0;

All this is weird. Why would you verify? You were matched, it cannot be
mis-matching.

> +	case SPX5_TARGET_CT_LAN9698RED:
> +		if (sparx5->target_ct == SPX5_TARGET_CT_LAN9698RED)

What is "ct"? sorry, all this code is a big no.

Best regards,
Krzysztof