linux-kernel - Re: [PATCH 2/4] soc: qcom: pmic_glink: Introduce base PMIC GLINK driver

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Date:   Mon, 24 Oct 2022 15:02:22 -0500
From:   Andrew Halaney <ahalaney@...hat.com>
To:     Bjorn Andersson <andersson@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Sebastian Reichel <sre@...nel.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        echanude@...hat.com
Subject: Re: [PATCH 2/4] soc: qcom: pmic_glink: Introduce base PMIC GLINK
 driver

On Wed, Aug 17, 2022 at 08:15:10PM -0700, Bjorn Andersson wrote:
> The PMIC GLINK service runs on one of the co-processors of some modern
> Qualcomm platforms and implements USB-C and battery managements. It uses
> a message based protocol over GLINK for communication with the OS, hence
> the name.
> 
> The driver implemented provides the rpmsg device for communication and
> uses auxilirary bus to spawn off individual devices in respsective
> subsystem. The auxilirary devices are spawned off from a
> platform_device, so that the drm_bridge is available early, to allow the
> DisplayPort driver to probe even before the remoteproc has spun up.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
<snip>
> diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
> new file mode 100644
> index 000000000000..d42127521eca
> --- /dev/null
> +++ b/drivers/soc/qcom/pmic_glink.c
> @@ -0,0 +1,336 @@
<snip>
> +
> +static void _devm_pmic_glink_release_client(struct device *dev, void *res)
> +{
> +	struct pmic_glink_client *client = *(struct pmic_glink_client **)res;

As Eric Chanudet pointed out to me, this should be:

	struct pmic_glink_client *client = (struct pmic_glink_client *)res;

Otherwise you get a splat like below (which somehow resulted in my
panel output not to work on my x13s... not sure of the connection
there, and is easily reproducible with a probe deferal or qcom_battmgr
unload):

        Unable to handle kernel NULL pointer dereference at virtual address 0000000000000958
        Mem abort info:
          ESR = 0x0000000096000004
          EC = 0x25: DABT (current EL), IL = 32 bits
          ESR = 0x0000000096000004
          EC = 0x25: DABT (current EL), IL = 32 bits
          SET = 0, FnV = 0
          EA = 0, S1PTW = 0
          FSC = 0x04: level 0 translation fault
        Data abort info:
          ISV = 0, ISS = 0x00000004
          CM = 0, WnR = 0
        user pgtable: 4k pages, 48-bit VAs, pgdp=0000000106b92000
        [0000000000000958] pgd=0000000000000000, p4d=0000000000000000
        Internal error: Oops: 96000004 [#1] PREEMPT SMP
        Modules linked in: llcc_qcom qcom_battmgr aes_ce_blk pmic_glink_altmode aes_ce_cipher ghash_ce gf128mul sha2_ce sha256_arm64 sha1_ce gpio_sbu_mux pmic_glink gpio_keys autofs4
        CPU: 2 PID: 182 Comm: kworker/u16:5 Not tainted 6.0.0-rc6 #29
        Hardware name: LENOVO 21BX0016US/21BX0016US, BIOS N3HET47W (1.19 ) 07/04/2022
        Workqueue: events_unbound deferred_probe_work_func
        pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
        pc : mutex_lock+0x1c/0x60
        lr : _devm_pmic_glink_release_client+0x2c/0x74 [pmic_glink]
        sp : ffff80000c553970
        x29: ffff80000c553970 x28: 0000000000000000 x27: 0000000000000000
        x26: ffffc297e181e0e8 x25: ffffc297e181d000 x24: ffffc2984efd9a80
        x23: ffffc2984ea7a008 x22: ffff1738863cc3a0 x21: ffff80000c553a28
        x20: 0000000000000958 x19: ffff1738863cc9f8 x18: ffffffffffffffff
        x17: 0000000000000000 x16: ffffc2984e1bb110 x15: 61622d6d6f63713d
        x14: ffffc2984f3b23e0 x13: 554e514553007972 x12: 0000000000000000
        x11: 00313731333d4d55 x10: 0000000000000000 x9 : ffffc297e181d1cc
        x8 : ffff80000c553910 x7 : 0000000000000000 x6 : 0000000080200016
        x5 : 0000000000000038 x4 : 0000000000000000 x3 : 0000000000000958
        x2 : ffff17388522c100 x1 : 0000000000000000 x0 : 0000000000000958
        Call trace:
         mutex_lock+0x1c/0x60
         release_nodes+0x68/0x100
         devres_release_all+0x94/0xf0
         device_unbind_cleanup+0x20/0x70
         device_release_driver_internal+0x214/0x260
         device_release_driver+0x20/0x30
         bus_remove_device+0xdc/0x170
         device_del+0x178/0x3ac
         pmic_glink_probe+0x1e8/0x240 [pmic_glink]
         platform_probe+0x70/0xcc
         really_probe+0xc8/0x3e0
         __driver_probe_device+0x84/0x190
         driver_probe_device+0x44/0x100
         __device_attach_driver+0xc4/0x160
         bus_for_each_drv+0x84/0xe0
         __device_attach+0xa4/0x1c4
         device_initial_probe+0x1c/0x30
         bus_probe_device+0xa4/0xb0
         deferred_probe_work_func+0xc0/0x114
         process_one_work+0x1ec/0x470
         worker_thread+0x74/0x410
         kthread+0xfc/0x110
         ret_from_fork+0x10/0x20
        Code: d5384102 d503201f d2800001 aa0103e4 (c8e47c02)
        ---[ end trace 0000000000000000 ]---

All credit to Eric[0] on that, I'm just tying up loose ends.

[0] https://gitlab.com/ahalaney/linux/-/commit/1819fbccd03de430d9fd4c58ded35f5be83e9aa8

Thanks,
Andrew