[PATCH 1/1] dma: actions: Fix lockdep splat for owl-dma

[PATCH 1/1] dma: actions: Fix lockdep splat for owl-dma

[Cristian Ciocaltea]

When the kernel is build with lockdep support and the owl-dma driver is
used, the following message is shown:

[    2.496939] INFO: trying to register non-static key.
[    2.501889] the code is fine but needs lockdep annotation.
[    2.507357] turning off the locking correctness validator.
[    2.512834] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.6.3+ #15
[    2.519084] Hardware name: Generic DT based system
[    2.523878] Workqueue: events_freezable mmc_rescan
[    2.528681] [<801127f0>] (unwind_backtrace) from [<8010da58>] (show_stack+0x10/0x14)
[    2.536420] [<8010da58>] (show_stack) from [<8080fbe8>] (dump_stack+0xb4/0xe0)
[    2.543645] [<8080fbe8>] (dump_stack) from [<8017efa4>] (register_lock_class+0x6f0/0x718)
[    2.551816] [<8017efa4>] (register_lock_class) from [<8017b7d0>] (__lock_acquire+0x78/0x25f0)
[    2.560330] [<8017b7d0>] (__lock_acquire) from [<8017e5e4>] (lock_acquire+0xd8/0x1f4)
[    2.568159] [<8017e5e4>] (lock_acquire) from [<80831fb0>] (_raw_spin_lock_irqsave+0x3c/0x50)
[    2.576589] [<80831fb0>] (_raw_spin_lock_irqsave) from [<8051b5fc>] (owl_dma_issue_pending+0xbc/0x120)
[    2.585884] [<8051b5fc>] (owl_dma_issue_pending) from [<80668cbc>] (owl_mmc_request+0x1b0/0x390)
[    2.594655] [<80668cbc>] (owl_mmc_request) from [<80650ce0>] (mmc_start_request+0x94/0xbc)
[    2.602906] [<80650ce0>] (mmc_start_request) from [<80650ec0>] (mmc_wait_for_req+0x64/0xd0)
[    2.611245] [<80650ec0>] (mmc_wait_for_req) from [<8065aa10>] (mmc_app_send_scr+0x10c/0x144)
[    2.619669] [<8065aa10>] (mmc_app_send_scr) from [<80659b3c>] (mmc_sd_setup_card+0x4c/0x318)
[    2.628092] [<80659b3c>] (mmc_sd_setup_card) from [<80659f0c>] (mmc_sd_init_card+0x104/0x430)
[    2.636601] [<80659f0c>] (mmc_sd_init_card) from [<8065a3e0>] (mmc_attach_sd+0xcc/0x16c)
[    2.644678] [<8065a3e0>] (mmc_attach_sd) from [<8065301c>] (mmc_rescan+0x3ac/0x40c)
[    2.652332] [<8065301c>] (mmc_rescan) from [<80143244>] (process_one_work+0x2d8/0x780)
[    2.660239] [<80143244>] (process_one_work) from [<80143730>] (worker_thread+0x44/0x598)
[    2.668323] [<80143730>] (worker_thread) from [<8014b5f8>] (kthread+0x148/0x150)
[    2.675708] [<8014b5f8>] (kthread) from [<801010b4>] (ret_from_fork+0x14/0x20)
[    2.682912] Exception stack(0xee8fdfb0 to 0xee8fdff8)
[    2.687954] dfa0:                                     00000000 00000000 00000000 00000000
[    2.696118] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    2.704277] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000

The required fix is to use spin_lock_init() on the pchan lock before
attempting to call any spin_lock_irqsave() in owl_dma_get_pchan().

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
---
 drivers/dma/owl-dma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
index c683051257fd..d9d0f0488e70 100644
--- a/drivers/dma/owl-dma.c
+++ b/drivers/dma/owl-dma.c
@@ -1131,6 +1131,7 @@ static int owl_dma_probe(struct platform_device *pdev)
 
 		pchan->id = i;
 		pchan->base = od->base + OWL_DMA_CHAN_BASE(i);
+		spin_lock_init(&pchan->lock);
 	}
 
 	/* Init virtual channel */
-- 
2.26.2

[PATCH 1/1] dma: actions: Fix lockdep splat for owl-dma

[Cristian Ciocaltea]

When the kernel is build with lockdep support and the owl-dma driver is
used, the following message is shown:

[    2.496939] INFO: trying to register non-static key.
[    2.501889] the code is fine but needs lockdep annotation.
[    2.507357] turning off the locking correctness validator.
[    2.512834] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.6.3+ #15
[    2.519084] Hardware name: Generic DT based system
[    2.523878] Workqueue: events_freezable mmc_rescan
[    2.528681] [<801127f0>] (unwind_backtrace) from [<8010da58>] (show_stack+0x10/0x14)
[    2.536420] [<8010da58>] (show_stack) from [<8080fbe8>] (dump_stack+0xb4/0xe0)
[    2.543645] [<8080fbe8>] (dump_stack) from [<8017efa4>] (register_lock_class+0x6f0/0x718)
[    2.551816] [<8017efa4>] (register_lock_class) from [<8017b7d0>] (__lock_acquire+0x78/0x25f0)
[    2.560330] [<8017b7d0>] (__lock_acquire) from [<8017e5e4>] (lock_acquire+0xd8/0x1f4)
[    2.568159] [<8017e5e4>] (lock_acquire) from [<80831fb0>] (_raw_spin_lock_irqsave+0x3c/0x50)
[    2.576589] [<80831fb0>] (_raw_spin_lock_irqsave) from [<8051b5fc>] (owl_dma_issue_pending+0xbc/0x120)
[    2.585884] [<8051b5fc>] (owl_dma_issue_pending) from [<80668cbc>] (owl_mmc_request+0x1b0/0x390)
[    2.594655] [<80668cbc>] (owl_mmc_request) from [<80650ce0>] (mmc_start_request+0x94/0xbc)
[    2.602906] [<80650ce0>] (mmc_start_request) from [<80650ec0>] (mmc_wait_for_req+0x64/0xd0)
[    2.611245] [<80650ec0>] (mmc_wait_for_req) from [<8065aa10>] (mmc_app_send_scr+0x10c/0x144)
[    2.619669] [<8065aa10>] (mmc_app_send_scr) from [<80659b3c>] (mmc_sd_setup_card+0x4c/0x318)
[    2.628092] [<80659b3c>] (mmc_sd_setup_card) from [<80659f0c>] (mmc_sd_init_card+0x104/0x430)
[    2.636601] [<80659f0c>] (mmc_sd_init_card) from [<8065a3e0>] (mmc_attach_sd+0xcc/0x16c)
[    2.644678] [<8065a3e0>] (mmc_attach_sd) from [<8065301c>] (mmc_rescan+0x3ac/0x40c)
[    2.652332] [<8065301c>] (mmc_rescan) from [<80143244>] (process_one_work+0x2d8/0x780)
[    2.660239] [<80143244>] (process_one_work) from [<80143730>] (worker_thread+0x44/0x598)
[    2.668323] [<80143730>] (worker_thread) from [<8014b5f8>] (kthread+0x148/0x150)
[    2.675708] [<8014b5f8>] (kthread) from [<801010b4>] (ret_from_fork+0x14/0x20)
[    2.682912] Exception stack(0xee8fdfb0 to 0xee8fdff8)
[    2.687954] dfa0:                                     00000000 00000000 00000000 00000000
[    2.696118] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    2.704277] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000

The required fix is to use spin_lock_init() on the pchan lock before
attempting to call any spin_lock_irqsave() in owl_dma_get_pchan().

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
---
 drivers/dma/owl-dma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
index c683051257fd..d9d0f0488e70 100644
--- a/drivers/dma/owl-dma.c
+++ b/drivers/dma/owl-dma.c
@@ -1131,6 +1131,7 @@ static int owl_dma_probe(struct platform_device *pdev)
 
 		pchan->id = i;
 		pchan->base = od->base + OWL_DMA_CHAN_BASE(i);
+		spin_lock_init(&pchan->lock);
 	}
 
 	/* Init virtual channel */
-- 
2.26.2

Re: [PATCH 1/1] dma: actions: Fix lockdep splat for owl-dma

[Manivannan Sadhasivam]

Hi,

On Tue, Apr 28, 2020 at 01:56:12PM +0300, Cristian Ciocaltea wrote:
> When the kernel is build with lockdep support and the owl-dma driver is
> used, the following message is shown:
> 
> [    2.496939] INFO: trying to register non-static key.
> [    2.501889] the code is fine but needs lockdep annotation.
> [    2.507357] turning off the locking correctness validator.
> [    2.512834] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.6.3+ #15
> [    2.519084] Hardware name: Generic DT based system
> [    2.523878] Workqueue: events_freezable mmc_rescan
> [    2.528681] [<801127f0>] (unwind_backtrace) from [<8010da58>] (show_stack+0x10/0x14)
> [    2.536420] [<8010da58>] (show_stack) from [<8080fbe8>] (dump_stack+0xb4/0xe0)
> [    2.543645] [<8080fbe8>] (dump_stack) from [<8017efa4>] (register_lock_class+0x6f0/0x718)
> [    2.551816] [<8017efa4>] (register_lock_class) from [<8017b7d0>] (__lock_acquire+0x78/0x25f0)
> [    2.560330] [<8017b7d0>] (__lock_acquire) from [<8017e5e4>] (lock_acquire+0xd8/0x1f4)
> [    2.568159] [<8017e5e4>] (lock_acquire) from [<80831fb0>] (_raw_spin_lock_irqsave+0x3c/0x50)
> [    2.576589] [<80831fb0>] (_raw_spin_lock_irqsave) from [<8051b5fc>] (owl_dma_issue_pending+0xbc/0x120)
> [    2.585884] [<8051b5fc>] (owl_dma_issue_pending) from [<80668cbc>] (owl_mmc_request+0x1b0/0x390)
> [    2.594655] [<80668cbc>] (owl_mmc_request) from [<80650ce0>] (mmc_start_request+0x94/0xbc)
> [    2.602906] [<80650ce0>] (mmc_start_request) from [<80650ec0>] (mmc_wait_for_req+0x64/0xd0)
> [    2.611245] [<80650ec0>] (mmc_wait_for_req) from [<8065aa10>] (mmc_app_send_scr+0x10c/0x144)
> [    2.619669] [<8065aa10>] (mmc_app_send_scr) from [<80659b3c>] (mmc_sd_setup_card+0x4c/0x318)
> [    2.628092] [<80659b3c>] (mmc_sd_setup_card) from [<80659f0c>] (mmc_sd_init_card+0x104/0x430)
> [    2.636601] [<80659f0c>] (mmc_sd_init_card) from [<8065a3e0>] (mmc_attach_sd+0xcc/0x16c)
> [    2.644678] [<8065a3e0>] (mmc_attach_sd) from [<8065301c>] (mmc_rescan+0x3ac/0x40c)
> [    2.652332] [<8065301c>] (mmc_rescan) from [<80143244>] (process_one_work+0x2d8/0x780)
> [    2.660239] [<80143244>] (process_one_work) from [<80143730>] (worker_thread+0x44/0x598)
> [    2.668323] [<80143730>] (worker_thread) from [<8014b5f8>] (kthread+0x148/0x150)
> [    2.675708] [<8014b5f8>] (kthread) from [<801010b4>] (ret_from_fork+0x14/0x20)
> [    2.682912] Exception stack(0xee8fdfb0 to 0xee8fdff8)
> [    2.687954] dfa0:                                     00000000 00000000 00000000 00000000
> [    2.696118] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [    2.704277] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
> 
> The required fix is to use spin_lock_init() on the pchan lock before
> attempting to call any spin_lock_irqsave() in owl_dma_get_pchan().
> 

Right, this is a bug. But while looking at the code now, I feel that we don't
need 'pchan->lock'. The idea was to protect 'pchan->vchan', but I think
'od->lock' is the better candidate for that since it already protects it in
'owl_dma_terminate_pchan'.

So I'd be happy if you remove the lock from 'pchan' and just directly use the
one in 'od'.

Out of curiosity, on which platform you're testing this?

Thanks,
Mani

> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
> ---
>  drivers/dma/owl-dma.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
> index c683051257fd..d9d0f0488e70 100644
> --- a/drivers/dma/owl-dma.c
> +++ b/drivers/dma/owl-dma.c
> @@ -1131,6 +1131,7 @@ static int owl_dma_probe(struct platform_device *pdev)
>  
>  		pchan->id = i;
>  		pchan->base = od->base + OWL_DMA_CHAN_BASE(i);
> +		spin_lock_init(&pchan->lock);
>  	}
>  
>  	/* Init virtual channel */
> -- 
> 2.26.2
> 

Re: [PATCH 1/1] dma: actions: Fix lockdep splat for owl-dma

[Cristian Ciocaltea]

On Tue, Apr 28, 2020 at 10:19:21PM +0530, Manivannan Sadhasivam wrote:
> Hi,
> 
> On Tue, Apr 28, 2020 at 01:56:12PM +0300, Cristian Ciocaltea wrote:
> > When the kernel is build with lockdep support and the owl-dma driver is
> > used, the following message is shown:
> > 
> > [    2.496939] INFO: trying to register non-static key.
> > [    2.501889] the code is fine but needs lockdep annotation.
> > [    2.507357] turning off the locking correctness validator.
> > [    2.512834] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.6.3+ #15
> > [    2.519084] Hardware name: Generic DT based system
> > [    2.523878] Workqueue: events_freezable mmc_rescan
> > [    2.528681] [<801127f0>] (unwind_backtrace) from [<8010da58>] (show_stack+0x10/0x14)
> > [    2.536420] [<8010da58>] (show_stack) from [<8080fbe8>] (dump_stack+0xb4/0xe0)
> > [    2.543645] [<8080fbe8>] (dump_stack) from [<8017efa4>] (register_lock_class+0x6f0/0x718)
> > [    2.551816] [<8017efa4>] (register_lock_class) from [<8017b7d0>] (__lock_acquire+0x78/0x25f0)
> > [    2.560330] [<8017b7d0>] (__lock_acquire) from [<8017e5e4>] (lock_acquire+0xd8/0x1f4)
> > [    2.568159] [<8017e5e4>] (lock_acquire) from [<80831fb0>] (_raw_spin_lock_irqsave+0x3c/0x50)
> > [    2.576589] [<80831fb0>] (_raw_spin_lock_irqsave) from [<8051b5fc>] (owl_dma_issue_pending+0xbc/0x120)
> > [    2.585884] [<8051b5fc>] (owl_dma_issue_pending) from [<80668cbc>] (owl_mmc_request+0x1b0/0x390)
> > [    2.594655] [<80668cbc>] (owl_mmc_request) from [<80650ce0>] (mmc_start_request+0x94/0xbc)
> > [    2.602906] [<80650ce0>] (mmc_start_request) from [<80650ec0>] (mmc_wait_for_req+0x64/0xd0)
> > [    2.611245] [<80650ec0>] (mmc_wait_for_req) from [<8065aa10>] (mmc_app_send_scr+0x10c/0x144)
> > [    2.619669] [<8065aa10>] (mmc_app_send_scr) from [<80659b3c>] (mmc_sd_setup_card+0x4c/0x318)
> > [    2.628092] [<80659b3c>] (mmc_sd_setup_card) from [<80659f0c>] (mmc_sd_init_card+0x104/0x430)
> > [    2.636601] [<80659f0c>] (mmc_sd_init_card) from [<8065a3e0>] (mmc_attach_sd+0xcc/0x16c)
> > [    2.644678] [<8065a3e0>] (mmc_attach_sd) from [<8065301c>] (mmc_rescan+0x3ac/0x40c)
> > [    2.652332] [<8065301c>] (mmc_rescan) from [<80143244>] (process_one_work+0x2d8/0x780)
> > [    2.660239] [<80143244>] (process_one_work) from [<80143730>] (worker_thread+0x44/0x598)
> > [    2.668323] [<80143730>] (worker_thread) from [<8014b5f8>] (kthread+0x148/0x150)
> > [    2.675708] [<8014b5f8>] (kthread) from [<801010b4>] (ret_from_fork+0x14/0x20)
> > [    2.682912] Exception stack(0xee8fdfb0 to 0xee8fdff8)
> > [    2.687954] dfa0:                                     00000000 00000000 00000000 00000000
> > [    2.696118] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > [    2.704277] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > 
> > The required fix is to use spin_lock_init() on the pchan lock before
> > attempting to call any spin_lock_irqsave() in owl_dma_get_pchan().
> > 
> 
> Right, this is a bug. But while looking at the code now, I feel that we don't
> need 'pchan->lock'. The idea was to protect 'pchan->vchan', but I think
> 'od->lock' is the better candidate for that since it already protects it in
> 'owl_dma_terminate_pchan'.
> 
> So I'd be happy if you remove the lock from 'pchan' and just directly use the
> one in 'od'.
> 
> Out of curiosity, on which platform you're testing this?
> 
> Thanks,
> Mani
> 

Hi Mani,

Totally agree, I will send a new patch revision as soon as I do some
more testing.

I'm currently experimenting on an Actions S500 based board (Roseapple Pi)
trying to extend, if possible, the existing mainline support for those
SoCs. I don't have much progress so far, since I started quite recently
and I also lack experience in the kernel development area, but I do my
best to come back with more patches once I get a consistent functionality.

Thanks a lot for your support,
Cristi

> > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
> > ---
> >  drivers/dma/owl-dma.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
> > index c683051257fd..d9d0f0488e70 100644
> > --- a/drivers/dma/owl-dma.c
> > +++ b/drivers/dma/owl-dma.c
> > @@ -1131,6 +1131,7 @@ static int owl_dma_probe(struct platform_device *pdev)
> >  
> >  		pchan->id = i;
> >  		pchan->base = od->base + OWL_DMA_CHAN_BASE(i);
> > +		spin_lock_init(&pchan->lock);
> >  	}
> >  
> >  	/* Init virtual channel */
> > -- 
> > 2.26.2
> > 

Re: [PATCH 1/1] dma: actions: Fix lockdep splat for owl-dma

[Manivannan Sadhasivam]

On Tue, Apr 28, 2020 at 09:11:15PM +0300, Cristian Ciocaltea wrote:
> On Tue, Apr 28, 2020 at 10:19:21PM +0530, Manivannan Sadhasivam wrote:
> > Hi,
> > 
> > On Tue, Apr 28, 2020 at 01:56:12PM +0300, Cristian Ciocaltea wrote:
> > > When the kernel is build with lockdep support and the owl-dma driver is
> > > used, the following message is shown:
> > > 
> > > [    2.496939] INFO: trying to register non-static key.
> > > [    2.501889] the code is fine but needs lockdep annotation.
> > > [    2.507357] turning off the locking correctness validator.
> > > [    2.512834] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.6.3+ #15
> > > [    2.519084] Hardware name: Generic DT based system
> > > [    2.523878] Workqueue: events_freezable mmc_rescan
> > > [    2.528681] [<801127f0>] (unwind_backtrace) from [<8010da58>] (show_stack+0x10/0x14)
> > > [    2.536420] [<8010da58>] (show_stack) from [<8080fbe8>] (dump_stack+0xb4/0xe0)
> > > [    2.543645] [<8080fbe8>] (dump_stack) from [<8017efa4>] (register_lock_class+0x6f0/0x718)
> > > [    2.551816] [<8017efa4>] (register_lock_class) from [<8017b7d0>] (__lock_acquire+0x78/0x25f0)
> > > [    2.560330] [<8017b7d0>] (__lock_acquire) from [<8017e5e4>] (lock_acquire+0xd8/0x1f4)
> > > [    2.568159] [<8017e5e4>] (lock_acquire) from [<80831fb0>] (_raw_spin_lock_irqsave+0x3c/0x50)
> > > [    2.576589] [<80831fb0>] (_raw_spin_lock_irqsave) from [<8051b5fc>] (owl_dma_issue_pending+0xbc/0x120)
> > > [    2.585884] [<8051b5fc>] (owl_dma_issue_pending) from [<80668cbc>] (owl_mmc_request+0x1b0/0x390)
> > > [    2.594655] [<80668cbc>] (owl_mmc_request) from [<80650ce0>] (mmc_start_request+0x94/0xbc)
> > > [    2.602906] [<80650ce0>] (mmc_start_request) from [<80650ec0>] (mmc_wait_for_req+0x64/0xd0)
> > > [    2.611245] [<80650ec0>] (mmc_wait_for_req) from [<8065aa10>] (mmc_app_send_scr+0x10c/0x144)
> > > [    2.619669] [<8065aa10>] (mmc_app_send_scr) from [<80659b3c>] (mmc_sd_setup_card+0x4c/0x318)
> > > [    2.628092] [<80659b3c>] (mmc_sd_setup_card) from [<80659f0c>] (mmc_sd_init_card+0x104/0x430)
> > > [    2.636601] [<80659f0c>] (mmc_sd_init_card) from [<8065a3e0>] (mmc_attach_sd+0xcc/0x16c)
> > > [    2.644678] [<8065a3e0>] (mmc_attach_sd) from [<8065301c>] (mmc_rescan+0x3ac/0x40c)
> > > [    2.652332] [<8065301c>] (mmc_rescan) from [<80143244>] (process_one_work+0x2d8/0x780)
> > > [    2.660239] [<80143244>] (process_one_work) from [<80143730>] (worker_thread+0x44/0x598)
> > > [    2.668323] [<80143730>] (worker_thread) from [<8014b5f8>] (kthread+0x148/0x150)
> > > [    2.675708] [<8014b5f8>] (kthread) from [<801010b4>] (ret_from_fork+0x14/0x20)
> > > [    2.682912] Exception stack(0xee8fdfb0 to 0xee8fdff8)
> > > [    2.687954] dfa0:                                     00000000 00000000 00000000 00000000
> > > [    2.696118] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > > [    2.704277] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > > 
> > > The required fix is to use spin_lock_init() on the pchan lock before
> > > attempting to call any spin_lock_irqsave() in owl_dma_get_pchan().
> > > 
> > 
> > Right, this is a bug. But while looking at the code now, I feel that we don't
> > need 'pchan->lock'. The idea was to protect 'pchan->vchan', but I think
> > 'od->lock' is the better candidate for that since it already protects it in
> > 'owl_dma_terminate_pchan'.
> > 
> > So I'd be happy if you remove the lock from 'pchan' and just directly use the
> > one in 'od'.
> > 
> > Out of curiosity, on which platform you're testing this?
> > 
> > Thanks,
> > Mani
> > 
> 
> Hi Mani,
> 
> Totally agree, I will send a new patch revision as soon as I do some
> more testing.
> 

Coo, thanks!

> I'm currently experimenting on an Actions S500 based board (Roseapple Pi)
> trying to extend, if possible, the existing mainline support for those
> SoCs.

Awesome! It's great to see that Actions platform is seeing some attention
these days :)

> I don't have much progress so far, since I started quite recently
> and I also lack experience in the kernel development area, but I do my
> best to come back with more patches once I get a consistent functionality.
> 

No worries. Feel free to reach out to me if you have any questions. There is
a lot of work to do and for sure it will be a good learning curve.

We do have an IRC channel (##linux-actions) for quick discussions. Fee free
to join!

Thanks,
Mani

> Thanks a lot for your support,
> Cristi
> 
> > > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
> > > ---
> > >  drivers/dma/owl-dma.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
> > > index c683051257fd..d9d0f0488e70 100644
> > > --- a/drivers/dma/owl-dma.c
> > > +++ b/drivers/dma/owl-dma.c
> > > @@ -1131,6 +1131,7 @@ static int owl_dma_probe(struct platform_device *pdev)
> > >  
> > >  		pchan->id = i;
> > >  		pchan->base = od->base + OWL_DMA_CHAN_BASE(i);
> > > +		spin_lock_init(&pchan->lock);
> > >  	}
> > >  
> > >  	/* Init virtual channel */
> > > -- 
> > > 2.26.2
> > > 

Re: [PATCH 1/1] dma: actions: Fix lockdep splat for owl-dma

[Andreas Färber]

Am 28.04.20 um 20:18 schrieb Manivannan Sadhasivam:
> On Tue, Apr 28, 2020 at 09:11:15PM +0300, Cristian Ciocaltea wrote:
>> On Tue, Apr 28, 2020 at 10:19:21PM +0530, Manivannan Sadhasivam wrote:
>>> On Tue, Apr 28, 2020 at 01:56:12PM +0300, Cristian Ciocaltea wrote:
>>>> When the kernel is build with lockdep support and the owl-dma driver is
>>>> used, the following message is shown:
[...]
>>>> The required fix is to use spin_lock_init() on the pchan lock before
>>>> attempting to call any spin_lock_irqsave() in owl_dma_get_pchan().
>>>
>>> Right, this is a bug. But while looking at the code now, I feel that we don't
>>> need 'pchan->lock'. The idea was to protect 'pchan->vchan', but I think
>>> 'od->lock' is the better candidate for that since it already protects it in
>>> 'owl_dma_terminate_pchan'.
>>>
>>> So I'd be happy if you remove the lock from 'pchan' and just directly use the
>>> one in 'od'.
>>>
>>> Out of curiosity, on which platform you're testing this?
>>
>> Totally agree, I will send a new patch revision as soon as I do some
>> more testing.
> 
> Coo[l], thanks!
> 
>> I'm currently experimenting on an Actions S500 based board (Roseapple Pi)
>> trying to extend, if possible, the existing mainline support for those
>> SoCs.
> 
> Awesome! It's great to see that Actions platform is seeing some attention
> these days :)
> 
>> I don't have much progress so far, since I started quite recently
>> and I also lack experience in the kernel development area, but I do my
>> best to come back with more patches once I get a consistent functionality.
> 
> No worries. Feel free to reach out to me if you have any questions. There is
> a lot of work to do and for sure it will be a good learning curve.
> 
> We do have an IRC channel (##linux-actions) for quick discussions. Fee[l] free
> to join!

Please also CC the linux-actions mailing list on any patches:

https://lists.infradead.org/mailman/listinfo/linux-actions

Mani, do you have a 5.7-rc1 tree set up or should I queue patches this 
round? It still seems missing in MAINTAINERS, and then there's Matheus' 
patches in review.

Thanks,
Andreas

-- 
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer
HRB 36809 (AG Nürnberg)

Re: [PATCH 1/1] dma: actions: Fix lockdep splat for owl-dma

[Manivannan Sadhasivam]

Hi Andreas,

On Wed, Apr 29, 2020 at 10:36:01AM +0200, Andreas Färber wrote:
> Am 28.04.20 um 20:18 schrieb Manivannan Sadhasivam:
> > On Tue, Apr 28, 2020 at 09:11:15PM +0300, Cristian Ciocaltea wrote:
> > > On Tue, Apr 28, 2020 at 10:19:21PM +0530, Manivannan Sadhasivam wrote:
> > > > On Tue, Apr 28, 2020 at 01:56:12PM +0300, Cristian Ciocaltea wrote:
> > > > > When the kernel is build with lockdep support and the owl-dma driver is
> > > > > used, the following message is shown:
> [...]
> > > > > The required fix is to use spin_lock_init() on the pchan lock before
> > > > > attempting to call any spin_lock_irqsave() in owl_dma_get_pchan().
> > > > 
> > > > Right, this is a bug. But while looking at the code now, I feel that we don't
> > > > need 'pchan->lock'. The idea was to protect 'pchan->vchan', but I think
> > > > 'od->lock' is the better candidate for that since it already protects it in
> > > > 'owl_dma_terminate_pchan'.
> > > > 
> > > > So I'd be happy if you remove the lock from 'pchan' and just directly use the
> > > > one in 'od'.
> > > > 
> > > > Out of curiosity, on which platform you're testing this?
> > > 
> > > Totally agree, I will send a new patch revision as soon as I do some
> > > more testing.
> > 
> > Coo[l], thanks!
> > 
> > > I'm currently experimenting on an Actions S500 based board (Roseapple Pi)
> > > trying to extend, if possible, the existing mainline support for those
> > > SoCs.
> > 
> > Awesome! It's great to see that Actions platform is seeing some attention
> > these days :)
> > 
> > > I don't have much progress so far, since I started quite recently
> > > and I also lack experience in the kernel development area, but I do my
> > > best to come back with more patches once I get a consistent functionality.
> > 
> > No worries. Feel free to reach out to me if you have any questions. There is
> > a lot of work to do and for sure it will be a good learning curve.
> > 
> > We do have an IRC channel (##linux-actions) for quick discussions. Fee[l] free
> > to join!
> 
> Please also CC the linux-actions mailing list on any patches:
> 
> https://lists.infradead.org/mailman/listinfo/linux-actions
> 
> Mani, do you have a 5.7-rc1 tree set up or should I queue patches this
> round?

I haven't set up the branch. You can do the maintainership duties for this
cycle.

> It still seems missing in MAINTAINERS, and then there's Matheus'
> patches in review.
> 

Yeah, the MAINTAINERS patch has fallen through cracks:

[PATCH v2 6/6] MAINTAINERS: Add linux-actions mailing list for Actions Semi

I did this as a part of S500 clk series. Feel free to pick it up.

Thanks,
Mani

> Thanks,
> Andreas
> 
> -- 
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> GF: Felix Imendörffer
> HRB 36809 (AG Nürnberg)