Re: [PATCH v5 4/4] usb: typec: ucsi: Always set number of alternate modes

[Jon Hunter <jonathanh@nvidia.com>]

Hi Jameson,

On 10/05/2024 21:12, Jameson Thies wrote:
> Providing the number of known alternate modes allows user space to
> determine when device registration has completed. Always register a
> number of known alternate modes for the partner and cable plug, even
> when the number of supported alternate modes is 0.
> 
> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Reviewed-by: Benson Leung <bleung@chromium.org>
> Signed-off-by: Jameson Thies <jthies@google.com>
> ---
> Changes in V5:
> - None.
> 
> Changes in V4:
> - None.
> 
> Changes in V3:
> - None.
> 
> Changes in V2:
> - None.
> 
>   drivers/usb/typec/ucsi/ucsi.c | 14 +++++++++++---
>   1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index bb6e57064513d..52a14bfe4107e 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -812,10 +812,11 @@ static int ucsi_check_altmodes(struct ucsi_connector *con)
>   	/* Ignoring the errors in this case. */
>   	if (con->partner_altmode[0]) {
>   		num_partner_am = ucsi_get_num_altmode(con->partner_altmode);
> -		if (num_partner_am > 0)
> -			typec_partner_set_num_altmodes(con->partner, num_partner_am);
> +		typec_partner_set_num_altmodes(con->partner, num_partner_am);
>   		ucsi_altmode_update_active(con);
>   		return 0;
> +	} else {
> +		typec_partner_set_num_altmodes(con->partner, 0);
>   	}
>   
>   	return ret;
> @@ -1138,7 +1139,7 @@ static int ucsi_check_connection(struct ucsi_connector *con)
>   static int ucsi_check_cable(struct ucsi_connector *con)
>   {
>   	u64 command;
> -	int ret;
> +	int ret, num_plug_am;
>   
>   	if (con->cable)
>   		return 0;
> @@ -1172,6 +1173,13 @@ static int ucsi_check_cable(struct ucsi_connector *con)
>   			return ret;
>   	}
>   
> +	if (con->plug_altmode[0]) {
> +		num_plug_am = ucsi_get_num_altmode(con->plug_altmode);
> +		typec_plug_set_num_altmodes(con->plug, num_plug_am);
> +	} else {
> +		typec_plug_set_num_altmodes(con->plug, 0);
> +	}
> +
>   	return 0;
>   }
>   

I am seeing the following panic on linux-next and bisect is pointing to
this commit.

[   16.411135] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000310
[   16.411716] Mem abort info:
[   16.411806]   ESR = 0x0000000096000044
[   16.412147]   EC = 0x25: DABT (current EL), IL = 32 bits
[   16.412465]   SET = 0, FnV = 0
[   16.412530]   EA = 0, S1PTW = 0
[   16.412778]   FSC = 0x04: level 0 translation fault
[   16.413084] Data abort info:
[   16.413149]   ISV = 0, ISS = 0x00000044, ISS2 = 0x00000000
[   16.413534]   CM = 0, WnR = 1, TnD = 0, TagAccess = 0
[   16.414163]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[   16.414649] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000101b2b000
[   16.414784] [0000000000000310] pgd=0000000000000000, p4d=0000000000000000
[   16.414940] Internal error: Oops: 0000000096000044 [#1] PREEMPT SMP
[   16.414946] Modules linked in: tegra210_adma(+) snd_soc_tegra210_ahub(+) drm backlight snd_soc_tegra_audio_graph_card snd_soc_audio_graph_card ucsi_ccg typec_ucsi crct10dif_ce snd_soc_simple_card_utils typec pwm_fan snd_soc_rt5659(+) snd_soc_rl6231 ina3221 pwm_tegra tegra_aconnect phy_tegra194_p2u snd_hda_codec_hdmi at24 snd_hda_tegra snd_hda_codec snd_hda_core lm90 tegra_xudc host1x pcie_tegra194 tegra_bpmp_thermal ip_tables x_tables ipv6
[   16.415056] CPU: 0 PID: 290 Comm: kworker/0:4 Not tainted 6.10.0-rc4-next-20240617-g76db4c64526c #1
[   16.415063] Hardware name: NVIDIA Jetson AGX Xavier Developer Kit (DT)
[   16.415067] Workqueue: events_long ucsi_init_work [typec_ucsi]
[   16.415082] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   16.415091] pc : typec_plug_set_num_altmodes+0x18/0x6c [typec]
[   16.415112] lr : ucsi_check_cable.part.0+0x228/0x280 [typec_ucsi]
[   16.415120] sp : ffff8000848bbca0
[   16.415123] x29: ffff8000848bbca0 x28: ffff000080e66000 x27: ffff80007adc96e8
[   16.415140] x26: ffff80007adc96f8 x25: ffff0000834510c0 x24: ffff000080e66010
[   16.415150] x23: ffff000080e6638c x22: ffff000080e664c0 x21: ffff000089c95800
[   16.415160] x20: 0000000000000000 x19: 0000000000000000 x18: ffffffffffffffff
[   16.415170] x17: 1e00000001000000 x16: c203000000000000 x15: 00656c6261632d30
[   16.415180] x14: ffff800082c922d8 x13: 0000000000000040 x12: 0000000000000228
[   16.415191] x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
[   16.415201] x8 : 3d45505954564544 x7 : 0063657079743d4d x6 : 0000000000000000
[   16.415212] x5 : ffff0000835ee780 x4 : ffff000080e66288 x3 : 0000000000000000
[   16.415223] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
[   16.415233] Call trace:
[   16.415236]  typec_plug_set_num_altmodes+0x18/0x6c [typec]
[   16.415255]  ucsi_check_cable.part.0+0x228/0x280 [typec_ucsi]
[   16.415264]  ucsi_init_work+0x8b4/0x9b8 [typec_ucsi]
[   16.415271]  process_one_work+0x150/0x294
[   16.415282]  worker_thread+0x2f4/0x3fc
[   16.415289]  kthread+0x118/0x11c
[   16.415296]  ret_from_fork+0x10/0x20
[   16.415310] Code: a9be7bfd 910003fd f9000bf3 aa0003f3 (b9031001)
[   16.521018] ata1: SATA link down (SStatus 0 SControl 300)
[   16.524401] ---[ end trace 0000000000000000 ]---


I have not looked any further yet, but wanted to report this. If you have
any thoughts let me know.

Thanks
Jon

-- 
nvpublic