linux-kernel - Re: [PATCH] mailbox: imx: Fix Tx doorbell shutdown path

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Date:   Thu, 1 Aug 2019 08:10:33 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Daniel Baluta <daniel.baluta@....com>
Cc:     shawnguo@...nel.org, jassisinghbrar@...il.com,
        s.hauer@...gutronix.de, linux-kernel@...r.kernel.org,
        linux-imx@....com, kernel@...gutronix.de, festevam@...il.com,
        linux-arm-kernel@...ts.infradead.org, hongxing.zhu@....com,
        aisheng.dong@....com
Subject: Re: [PATCH] mailbox: imx: Fix Tx doorbell shutdown path

Hi Daniel,

your patch is in conflicht with Richard's Zhu <hongxing.zhu@....com>
patch "[PATCH v3] mailbox: imx: add support for imx v1 mu".
Please sync your works.

On Wed, Jul 31, 2019 at 11:55:39PM +0300, Daniel Baluta wrote:
> Tx doorbell is handled by txdb_tasklet and doesn't
> have an associated IRQ.
> 
> Anyhow, imx_mu_shutdown ignores this and tries to
> free an IRQ that wasn't requested for Tx DB resulting
> in the following warning:
> 
> [    1.967644] Trying to free already-free IRQ 26
> [    1.972108] WARNING: CPU: 2 PID: 157 at kernel/irq/manage.c:1708 __free_irq+0xc0/0x358
> [    1.980024] Modules linked in:
> [    1.983088] CPU: 2 PID: 157 Comm: kworker/2:1 Tainted: G
> [    1.993524] Hardware name: Freescale i.MX8QXP MEK (DT)
> [    1.998668] Workqueue: events deferred_probe_work_func
> [    2.003812] pstate: 60000085 (nZCv daIf -PAN -UAO)
> [    2.008607] pc : __free_irq+0xc0/0x358
> [    2.012364] lr : __free_irq+0xc0/0x358
> [    2.016111] sp : ffff00001179b7e0
> [    2.019422] x29: ffff00001179b7e0 x28: 0000000000000018
> [    2.024736] x27: ffff000011233000 x26: 0000000000000004
> [    2.030053] x25: 000000000000001a x24: ffff80083bec74d4
> [    2.035369] x23: 0000000000000000 x22: ffff80083bec7588
> [    2.040686] x21: ffff80083b1fe8d8 x20: ffff80083bec7400
> [    2.046003] x19: 0000000000000000 x18: ffffffffffffffff
> [    2.051320] x17: 0000000000000000 x16: 0000000000000000
> [    2.056637] x15: ffff0000111296c8 x14: ffff00009179b517
> [    2.061953] x13: ffff00001179b525 x12: ffff000011142000
> [    2.067270] x11: ffff000011129f20 x10: ffff0000105da970
> [    2.072587] x9 : 00000000ffffffd0 x8 : 0000000000000194
> [    2.077903] x7 : 612065657266206f x6 : ffff0000111e7b09
> [    2.083220] x5 : 0000000000000003 x4 : 0000000000000000
> [    2.088537] x3 : 0000000000000000 x2 : 00000000ffffffff
> [    2.093854] x1 : 28b70f0a2b60a500 x0 : 0000000000000000
> [    2.099173] Call trace:
> [    2.101618]  __free_irq+0xc0/0x358
> [    2.105021]  free_irq+0x38/0x98
> [    2.108170]  imx_mu_shutdown+0x90/0xb0
> [    2.111921]  mbox_free_channel.part.2+0x24/0xb8
> [    2.116453]  mbox_free_channel+0x18/0x28
> 
> This bug is present from the beginning of times.
> 
> Cc: Oleksij Rempel <o.rempel@...gutronix.de>
> Fixes:  2bb7005696e2246 ("mailbox: Add support for i.MX messaging unit")
> Signed-off-by: Daniel Baluta <daniel.baluta@....com>
> ---
>  drivers/mailbox/imx-mailbox.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mailbox/imx-mailbox.c b/drivers/mailbox/imx-mailbox.c
> index 9f74dee1a58c..957c10c4e674 100644
> --- a/drivers/mailbox/imx-mailbox.c
> +++ b/drivers/mailbox/imx-mailbox.c
> @@ -214,8 +214,10 @@ static void imx_mu_shutdown(struct mbox_chan *chan)
>  	struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
>  	struct imx_mu_con_priv *cp = chan->con_priv;
>  
> -	if (cp->type == IMX_MU_TYPE_TXDB)
> +	if (cp->type == IMX_MU_TYPE_TXDB) {
>  		tasklet_kill(&cp->txdb_tasklet);
> +		return;
> +	}
>  
>  	imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_TIEn(cp->idx) |
>  		       IMX_MU_xCR_RIEn(cp->idx) | IMX_MU_xCR_GIEn(cp->idx));

Looks like here is one more bug "from the beginning of times" :)
The imx_mu_xcr_rmw() should disable only one channel depending on the
type of channel.

It should be:
	switch (cp->type) {
	case IMX_MU_TYPE_TX:
		imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_TIEn(cp->idx));
		break;
	case IMX_MU_TYPE_RX:
		imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_RIEn(cp->idx));
		break;
	case IMX_MU_TYPE_RXDB:
		imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_GIEn(cp->idx));
		break;
	default:
		break;
	}

Right now I'm on vocation and have nothing against, if you'll provide
this fix.

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