[PATCH] mmc: davinci_mmc: add warnings for edma failures

[PATCH] mmc: davinci_mmc: add warnings for edma failures

[Angelo Dureghello]

Add warnings in case the edma engine driver fails to allocate slots or 
channels requested from the davinci_mmc driver.

Some ti-davinci based boards (i.e. board-da850-evm.c) are asking for
some reserved chans / slots at board init stage. Later, the mmc driver
results in a silent locked state.

Signed-off-by: Angelo Dureghello <angelo <at> sysam.it>

diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
index 5d4c5e0..65d4990 100644
--- a/drivers/mmc/host/davinci_mmc.c
+++ b/drivers/mmc/host/davinci_mmc.c
@@ -439,8 +439,8 @@ static int mmc_davinci_send_dma_request(struct 
mmc_davinci_host *host,
                                 DMA_MEM_TO_DEV,
                                 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                 if (!desc) {
-                       dev_dbg(mmc_dev(host->mmc),
-                               "failed to allocate DMA TX descriptor");
+                       WARN(1, KERN_WARNING
+                               "failed to allocate DMA TX descriptor\n");
                         ret = -1;
                         goto out;
                 }
@@ -461,8 +461,8 @@ static int mmc_davinci_send_dma_request(struct 
mmc_davinci_host *host,
                                 DMA_DEV_TO_MEM,
                                 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                 if (!desc) {
-                       dev_dbg(mmc_dev(host->mmc),
-                               "failed to allocate DMA RX descriptor");
+                       WARN(1, KERN_WARNING
+                               "failed to allocate DMA RX descriptor\n");
                         ret = -1;
                         goto out;
                 }

Fwd: [PATCH] mmc: davinci_mmc: add warnings for edma failures

[Angelo Dureghello]

Dear all,

would like some feedback / comment to this patch.

Even a NACK is good if you find it nonsense or un-useful, just
to close the loop.

Regards
angelo


-------- Original Message --------
Message-ID: <546FD21C.7010208@sysam.it>
Date: Sat, 22 Nov 2014 01:00:28 +0100
From: Angelo Dureghello <angelo@sysam.it>
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 
Icedove/24.5.0
MIME-Version: 1.0
To: linux-mmc@vger.kernel.org
Subject: [PATCH] mmc: davinci_mmc: add warnings for edma failures
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
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Add warnings in case the edma engine driver fails to allocate slots or
channels requested from the davinci_mmc driver.

Some ti-davinci based boards (i.e. board-da850-evm.c) are asking for
some reserved chans / slots at board init stage. Later, the mmc driver
results in a silent locked state.

Signed-off-by: Angelo Dureghello <angelo <at> sysam.it>

diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
index 5d4c5e0..65d4990 100644
--- a/drivers/mmc/host/davinci_mmc.c
+++ b/drivers/mmc/host/davinci_mmc.c
@@ -439,8 +439,8 @@ static int mmc_davinci_send_dma_request(struct
mmc_davinci_host *host,
                                 DMA_MEM_TO_DEV,
                                 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                 if (!desc) {
-                       dev_dbg(mmc_dev(host->mmc),
-                               "failed to allocate DMA TX descriptor");
+                       WARN(1, KERN_WARNING
+                               "failed to allocate DMA TX descriptor\n");
                         ret = -1;
                         goto out;
                 }
@@ -461,8 +461,8 @@ static int mmc_davinci_send_dma_request(struct
mmc_davinci_host *host,
                                 DMA_DEV_TO_MEM,
                                 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                 if (!desc) {
-                       dev_dbg(mmc_dev(host->mmc),
-                               "failed to allocate DMA RX descriptor");
+                       WARN(1, KERN_WARNING
+                               "failed to allocate DMA RX descriptor\n");
                         ret = -1;
                         goto out;
                 }

Re: [PATCH] mmc: davinci_mmc: add warnings for edma failures

[Ulf Hansson]

On 22 November 2014 at 01:00, Angelo Dureghello <angelo@sysam.it> wrote:
> Add warnings in case the edma engine driver fails to allocate slots or
> channels requested from the davinci_mmc driver.
>
> Some ti-davinci based boards (i.e. board-da850-evm.c) are asking for
> some reserved chans / slots at board init stage. Later, the mmc driver
> results in a silent locked state.

So why does davinci_acquire_dma_channels() succeed then? Isn't that
real problem you should be looking into?

Kind regards
Uffe

>
> Signed-off-by: Angelo Dureghello <angelo <at> sysam.it>
>
> diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
> index 5d4c5e0..65d4990 100644
> --- a/drivers/mmc/host/davinci_mmc.c
> +++ b/drivers/mmc/host/davinci_mmc.c
> @@ -439,8 +439,8 @@ static int mmc_davinci_send_dma_request(struct
> mmc_davinci_host *host,
>                                 DMA_MEM_TO_DEV,
>                                 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
>                 if (!desc) {
> -                       dev_dbg(mmc_dev(host->mmc),
> -                               "failed to allocate DMA TX descriptor");
> +                       WARN(1, KERN_WARNING
> +                               "failed to allocate DMA TX descriptor\n");
>                         ret = -1;
>                         goto out;
>                 }
> @@ -461,8 +461,8 @@ static int mmc_davinci_send_dma_request(struct
> mmc_davinci_host *host,
>                                 DMA_DEV_TO_MEM,
>                                 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
>                 if (!desc) {
> -                       dev_dbg(mmc_dev(host->mmc),
> -                               "failed to allocate DMA RX descriptor");
> +                       WARN(1, KERN_WARNING
> +                               "failed to allocate DMA RX descriptor\n");
>                         ret = -1;
>                         goto out;
>                 }
>
> --
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] mmc: davinci_mmc: add warnings for edma failures

[Angelo Dureghello]

Hi Uffe,

many hanks for the reply,

 >> Add warnings in case the edma engine driver fails to allocate slots or
 >> channels requested from the davinci_mmc driver.
 >>
 >> Some ti-davinci based boards (i.e. board-da850-evm.c) are asking for
 >> some reserved chans / slots at board init stage. Later, the mmc driver
 >> results in a silent locked state.
 >
 > So why does davinci_acquire_dma_channels() succeed then? Isn't that
 > real problem you should be looking into?

i explain with more details,

my custom am1808 board initialization, based on 
arch/arm/mach-davinci/board-da850-evm.c, reserves some dma chans / slots 
for the audio at
early boot.

While on kernel 3.5.1 mmc was working properly, moving to kernel
3.17.0, due to the dma-engine wrapper introduction (to be selected
into menuconfig), the mmc host driver locks silently. System cannot
even "reboot" after the failed attempt to reserve the dma slots.

I hardly found out the reason due to missing of clear warnings.

So there is nothing to fix in any other place. Simply, i am suggesting
a more visible warning so the driver, instead of lock-up silently,
throws a problem.

Feel free to add or discard the patch, as you can see it is nothing 
functional.

Regards,
Angelo

Re: [PATCH] mmc: davinci_mmc: add warnings for edma failures

[Ulf Hansson]

On 27 November 2014 at 11:18, Angelo Dureghello <angelo@sysam.it> wrote:
> Hi Uffe,
>
> many hanks for the reply,
>
>>> Add warnings in case the edma engine driver fails to allocate slots or
>>> channels requested from the davinci_mmc driver.
>>>
>>> Some ti-davinci based boards (i.e. board-da850-evm.c) are asking for
>>> some reserved chans / slots at board init stage. Later, the mmc driver
>>> results in a silent locked state.
>>
>> So why does davinci_acquire_dma_channels() succeed then? Isn't that
>> real problem you should be looking into?
>
> i explain with more details,
>
> my custom am1808 board initialization, based on
> arch/arm/mach-davinci/board-da850-evm.c, reserves some dma chans / slots for
> the audio at
> early boot.
>
> While on kernel 3.5.1 mmc was working properly, moving to kernel
> 3.17.0, due to the dma-engine wrapper introduction (to be selected
> into menuconfig), the mmc host driver locks silently. System cannot
> even "reboot" after the failed attempt to reserve the dma slots.
>
> I hardly found out the reason due to missing of clear warnings.
>
> So there is nothing to fix in any other place. Simply, i am suggesting
> a more visible warning so the driver, instead of lock-up silently,
> throws a problem.

I understand, thanks for clarifying.

So apparently the error handling for this path isn't working. I think
we should fix that instead of just WARN about it.

Kind regards
Uffe