linux-kernel - Re: [PATCH 4/8] thunderbolt: Do not fail adding switch if some port is not implemented

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Date:   Sat, 3 Aug 2019 16:14:01 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org,
        Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>
Subject: Re: [PATCH 4/8] thunderbolt: Do not fail adding switch if some port
 is not implemented

On Fri, Jul 05, 2019 at 12:57:56PM +0300, Mika Westerberg wrote:
> There are two ways to mark a port as unimplemented. Typical way is to
> return port type as TB_TYPE_INACTIVE when its config space is read.
> Alternatively if the port is not physically present (such as ports 10
> and 11 in ICL) reading from port config space returns
> TB_CFG_ERROR_INVALID_CONFIG_SPACE instead. Currently the driver bails
> out from adding the switch if it receives any error during port
> inititialization which is wrong.
> 
> Handle this properly and just leave the port as TB_TYPE_INACTIVE before
> continuing to the next port.

Your patch may also cause this snippet in eeprom.c to become obsolete:

		/* Port 5 is inaccessible on this gen 1 controller */
		if (sw->config.device_id == PCI_DEVICE_ID_INTEL_LIGHT_RIDGE)
			sw->ports[5].disabled = true;

To verify this hypothesis, one needs to comment out the call to
tb_drom_copy_efi() as well as the above-quoted snippet and boot
on a Mac with Light Ridge.  The driver should hit an error without
your patch and it may work correctly with your patch.

Thanks,

Lukas