Re: driver question about memory and calloc

[Adam Feuer]

The problem was that the interrupts the driver was waiting for (wait
interrupts) did not include SDMMC_INT_DINT, the DMA Boundary Pause
interrupt.

The calloc() / kmm_memalign() memory allocation put the buffer in a place
where the SDMA Buffer Boundary was not encountered, so the SDMA Boundary
Pause didn't happen. When I removed the extra memory allocation, the SDMA
Boundary Pause happened, but:

   1. The interrupts that the driver was waiting for didn't include the DMA
   Boundary Pause interrupt, so the driver never got a signal to wake up and
   restart the SDMA transfer
   2. The driver wasn't handling SDMA Boundary Pause interrupts, so I had
   to add handling code for it.

Just writing this here in case it helps anyone looking for how this was
solved.

I'm back on track.

-adam

On Wed, Jul 8, 2020 at 2:22 PM Adam Feuer  wrote:

> The kmm_malloc() also has the same effect of making it work.
>
> I think what's going on is that the transfer is passing a SDMA Buffer
> Boundary— they are 4kb (configurable, but that's the default). SDMA pauses
> when passing one, and needs to be reenabled by software. I can see the
> SDMMC_INT_DINT being fired when I dump the SDMMC registers, but that
> interrupt is not enabled for some reason... I'm trying to track it down now.
>
> -adam
>
> On Tue, Jul 7, 2020 at 9:09 PM Adam Feuer  wrote:
>
>> Greg,
>>
>> Thanks. I'll change the call to kmm_malloc() or kmm_memalign() and see if
>> that works too.
>>
>> cheers
>> adam
>>
>> On Tue, Jul 7, 2020 at 9:03 PM spudaneco  wrote:
>>
>>> I don't know anything about the DMA, but you should not call calloc()
>>> from within the OS.  That does not work in all configurations.Instead
>>> include nuttx/kmalloc,h and call kmm_malloc().  If you want aligned memory,
>>> call kmm_memalgn().Sent from Samsung tablet.
>>> ---- Original message ----From: Adam Feuer 
>>> Date: 7/7/20  9:40 PM  (GMT-06:00) To: dev@nuttx.apache.org Subject:
>>> driver question about memory and calloc Hi,I am getting the SAMA5D27 SDMMC
>>> SD Card driver pull request ready. There'sone small issue I'm working on,
>>> though. There's a place in the driverinitialization where I calloc() some
>>> memory– 466 bytes. DMA data transferswhile reading from files times out if
>>> I don't have the calloc() in there.With the memory allocated, everything
>>> works fine. Nothing writes to thisblock of memory– I memset it and examined
>>> it before, during, and aftertransfers using GDB. It's just an unused block
>>> of memory.I'm trying to find out if other amounts of memory work– smaller
>>> than about100 bytes doesn't work, and I know it works reliably at 466
>>> bytes. I'lltrack the exact number down tomorrow.But my question is, why
>>> does this work? The driver datasheets<
>>> http://ww1.microchip.com/downloads/en/devicedoc/ds60001476b.pdf>don'tmention
>>> that the chip needs aligned memory for its buffers, and the Atmeland U-Boot
>>> drivers don't use aligned memory. And since nothing isoverwriting the
>>> memory, what is the calloc() doing to prevent the SDMMC DMAengine from
>>> completing the transfer?If anyone has seen behavior like this, I'd love to
>>> know it. I'd like totake this otherwise useless code out, or at least know
>>> why I need it.Link to the specific line of code in sam_sdmmc.c<
>>> https://github.com/starcat-io/incubator-nuttx/blob/feature/sama5d27-sdmmc-support/arch/arm/src/sama5/sam_sdmmc.c#L3737>cheersadam--
>>> Adam Feuer 
>>
>>
>>
>> --
>> Adam Feuer 
>>
>
>
> --
> Adam Feuer 
>


-- 
Adam Feuer 

Re: driver question about memory and calloc

[Adam Feuer]

The kmm_malloc() also has the same effect of making it work.

I think what's going on is that the transfer is passing a SDMA Buffer
Boundary— they are 4kb (configurable, but that's the default). SDMA pauses
when passing one, and needs to be reenabled by software. I can see the
SDMMC_INT_DINT being fired when I dump the SDMMC registers, but that
interrupt is not enabled for some reason... I'm trying to track it down now.

-adam

On Tue, Jul 7, 2020 at 9:09 PM Adam Feuer  wrote:

> Greg,
>
> Thanks. I'll change the call to kmm_malloc() or kmm_memalign() and see if
> that works too.
>
> cheers
> adam
>
> On Tue, Jul 7, 2020 at 9:03 PM spudaneco  wrote:
>
>> I don't know anything about the DMA, but you should not call calloc()
>> from within the OS.  That does not work in all configurations.Instead
>> include nuttx/kmalloc,h and call kmm_malloc().  If you want aligned memory,
>> call kmm_memalgn().Sent from Samsung tablet.
>>  Original message From: Adam Feuer 
>> Date: 7/7/20  9:40 PM  (GMT-06:00) To: dev@nuttx.apache.org Subject:
>> driver question about memory and calloc Hi,I am getting the SAMA5D27 SDMMC
>> SD Card driver pull request ready. There'sone small issue I'm working on,
>> though. There's a place in the driverinitialization where I calloc() some
>> memory– 466 bytes. DMA data transferswhile reading from files times out if
>> I don't have the calloc() in there.With the memory allocated, everything
>> works fine. Nothing writes to thisblock of memory– I memset it and examined
>> it before, during, and aftertransfers using GDB. It's just an unused block
>> of memory.I'm trying to find out if other amounts of memory work– smaller
>> than about100 bytes doesn't work, and I know it works reliably at 466
>> bytes. I'lltrack the exact number down tomorrow.But my question is, why
>> does this work? The driver datasheets<
>> http://ww1.microchip.com/downloads/en/devicedoc/ds60001476b.pdf>don'tmention
>> that the chip needs aligned memory for its buffers, and the Atmeland U-Boot
>> drivers don't use aligned memory. And since nothing isoverwriting the
>> memory, what is the calloc() doing to prevent the SDMMC DMAengine from
>> completing the transfer?If anyone has seen behavior like this, I'd love to
>> know it. I'd like totake this otherwise useless code out, or at least know
>> why I need it.Link to the specific line of code in sam_sdmmc.c<
>> https://github.com/starcat-io/incubator-nuttx/blob/feature/sama5d27-sdmmc-support/arch/arm/src/sama5/sam_sdmmc.c#L3737>cheersadam--
>> Adam Feuer 
>
>
>
> --
> Adam Feuer 
>


-- 
Adam Feuer 

Re: driver question about memory and calloc

[Adam Feuer]

Greg,

Thanks. I'll change the call to kmm_malloc() or kmm_memalign() and see if
that works too.

cheers
adam

On Tue, Jul 7, 2020 at 9:03 PM spudaneco  wrote:

> I don't know anything about the DMA, but you should not call calloc() from
> within the OS.  That does not work in all configurations.Instead  include
> nuttx/kmalloc,h and call kmm_malloc().  If you want aligned memory, call
> kmm_memalgn().Sent from Samsung tablet.
>  Original message From: Adam Feuer 
> Date: 7/7/20  9:40 PM  (GMT-06:00) To: dev@nuttx.apache.org Subject:
> driver question about memory and calloc Hi,I am getting the SAMA5D27 SDMMC
> SD Card driver pull request ready. There'sone small issue I'm working on,
> though. There's a place in the driverinitialization where I calloc() some
> memory– 466 bytes. DMA data transferswhile reading from files times out if
> I don't have the calloc() in there.With the memory allocated, everything
> works fine. Nothing writes to thisblock of memory– I memset it and examined
> it before, during, and aftertransfers using GDB. It's just an unused block
> of memory.I'm trying to find out if other amounts of memory work– smaller
> than about100 bytes doesn't work, and I know it works reliably at 466
> bytes. I'lltrack the exact number down tomorrow.But my question is, why
> does this work? The driver datasheets<
> http://ww1.microchip.com/downloads/en/devicedoc/ds60001476b.pdf>don'tmention
> that the chip needs aligned memory for its buffers, and the Atmeland U-Boot
> drivers don't use aligned memory. And since nothing isoverwriting the
> memory, what is the calloc() doing to prevent the SDMMC DMAengine from
> completing the transfer?If anyone has seen behavior like this, I'd love to
> know it. I'd like totake this otherwise useless code out, or at least know
> why I need it.Link to the specific line of code in sam_sdmmc.c<
> https://github.com/starcat-io/incubator-nuttx/blob/feature/sama5d27-sdmmc-support/arch/arm/src/sama5/sam_sdmmc.c#L3737>cheersadam--
> Adam Feuer 



-- 
Adam Feuer 

RE: driver question about memory and calloc

[spudaneco]

I don't know anything about the DMA, but you should not call calloc() from 
within the OS.  That does not work in all configurations.Instead  include 
nuttx/kmalloc,h and call kmm_malloc().  If you want aligned memory, call 
kmm_memalgn().Sent from Samsung tablet.
 Original message From: Adam Feuer  Date: 
7/7/20  9:40 PM  (GMT-06:00) To: dev@nuttx.apache.org Subject: driver question 
about memory and calloc Hi,I am getting the SAMA5D27 SDMMC SD Card driver pull 
request ready. There'sone small issue I'm working on, though. There's a place 
in the driverinitialization where I calloc() some memory– 466 bytes. DMA data 
transferswhile reading from files times out if I don't have the calloc() in 
there.With the memory allocated, everything works fine. Nothing writes to 
thisblock of memory– I memset it and examined it before, during, and 
aftertransfers using GDB. It's just an unused block of memory.I'm trying to 
find out if other amounts of memory work– smaller than about100 bytes doesn't 
work, and I know it works reliably at 466 bytes. I'lltrack the exact number 
down tomorrow.But my question is, why does this work? The driver 
datasheets<http://ww1.microchip.com/downloads/en/devicedoc/ds60001476b.pdf>don'tmention
 that the chip needs aligned memory for its buffers, and the Atmeland U-Boot 
drivers don't use aligned memory. And since nothing isoverwriting the memory, 
what is the calloc() doing to prevent the SDMMC DMAengine from completing the 
transfer?If anyone has seen behavior like this, I'd love to know it. I'd like 
totake this otherwise useless code out, or at least know why I need it.Link to 
the specific line of code in 
sam_sdmmc.c<https://github.com/starcat-io/incubator-nuttx/blob/feature/sama5d27-sdmmc-support/arch/arm/src/sama5/sam_sdmmc.c#L3737>cheersadam--
 Adam Feuer 

driver question about memory and calloc

[Adam Feuer]

Hi,

I am getting the SAMA5D27 SDMMC SD Card driver pull request ready. There's
one small issue I'm working on, though. There's a place in the driver
initialization where I calloc() some memory– 466 bytes. DMA data transfers
while reading from files times out if I don't have the calloc() in there.
With the memory allocated, everything works fine. Nothing writes to this
block of memory– I memset it and examined it before, during, and after
transfers using GDB. It's just an unused block of memory.

I'm trying to find out if other amounts of memory work– smaller than about
100 bytes doesn't work, and I know it works reliably at 466 bytes. I'll
track the exact number down tomorrow.

But my question is, why does this work? The driver datasheets
don't
mention that the chip needs aligned memory for its buffers, and the Atmel
and U-Boot drivers don't use aligned memory. And since nothing is
overwriting the memory, what is the calloc() doing to prevent the SDMMC DMA
engine from completing the transfer?

If anyone has seen behavior like this, I'd love to know it. I'd like to
take this otherwise useless code out, or at least know why I need it.

Link to the specific line of code in sam_sdmmc.c


cheers
adam
-- 
Adam Feuer