[U-Boot] [PATCH] Use common function to set GPIOs for MX3 and MX5

[Stefano Babic]

David Jander wrote:
> Hi Stefano,
>

Hi David,

> On Friday 20 August 2010 01:19:28 pm Stefano Babic wrote:
>>> Will do.
>>> Btw, do you have any idea why spi_xchg_single() hangs while transmitting
>>> the second word without claiming the bus again?
>> Can you see where does it hang ? Which device is connected to your SPI
>> bus ? Does it work with the pmic (I think so, see later...).
> 
> Just figured out one big mistake. I was debugging spi_flash.c, and had 
> CONFIG_ENV_IS_IN_SPI_FLASH set. That means, first SPI access is done before 
> malloc is available, and guess what? spi_setup_slave() uses malloc ;-)

I have CONFIG_ENV_IS_IN_SPI_FLASH set, too.
I try to figure out how the functions are called, but I do not get the
same issue. I set with the debugger two breakpoints, one in
mem_malloc_init and the second one in spi_setup_slave. I see that
mem_alloc_init is hit first, and when spi_setup_slave is called, malloc
is available. I get a valid pointer for the private structure. It seems
there something in our config files that makes the things different. I
do not yet know why.

> The C++ comments show original code, the line below is new.

Understood, if malloc is not called, we have to use static or (better)
try to call mem_malloc_init() first

> I see a one byte access followed by a 5 byte access,

That is correct, you see the code in spi_flash.c. First the ID command
is sent (0x97), without reading nothing (that is, din is NULL). Then the
answer is read (dout is NULL), and the id buffer is 5 bytes long.

> I assumed that u-boot spi drivers use only u8 buffers for simplicity.
> So my fix looks as this:
> 
> int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
> 		void *din, unsigned long flags)
> {
> 	int n_blks = (bitlen + 31) / 32;
> 	u32 out, in;
> 	u8 *in_b, *out_b;
> 	int i;
> 	
> 	out_b = (u8 *)dout;
> 	in_b = (u8 *)din;
> 	
> 	for(i = 0; i< n_blks; i++, bitlen -= 32) {
> 		if(dout) {
> 			out = out_b[0];
> 			if(bitlen > 8)
> 				out = (out<<8) | out_b[1];
> 			if(bitlen > 16)
> 				out = (out<<8) | out_b[2];
> 			if(bitlen > 24)
> 				out = (out<<8) | out_b[3];
> 			out_b += 4;
> 		} else {
> 			out=0;
> 		}
> 		in = spi_xchg_single(slave, out, bitlen, flags);
> 		if(din) {
> 			if(bitlen > 24) {
> 				in_b[3] = in & 0xff;
> 				in >>= 8;
> 			}
> 			if(bitlen > 16) {
> 				in_b[2] = in & 0xff;
> 				in >>= 8;
> 			}
> 			if(bitlen > 8) {
> 				in_b[1] = in & 0xff;
> 				in >>= 8;
> 			}
> 			in_b[0] = in & 0xff;
> 			in_b += 4;
> 		}
> 	}
> 	return 0;
> }
> 
> Does this sound like it could work?

I am trying another approach. As the MX51 has 32 bytes FIFO, it makes
sense to use it and not send a single word, if we can. This must not
change the behavior for the MX31, because this processor has no FIFO and
a single word can be sent.
So I replaced completely spi_xfer, and the logic you put in spi_xfer I
have (more or less, I have not checked in details) moved inside the
spi_xcgh:single, that now has the meaning for me as single transation:
up to 1 word for i.MX31, up to 32 words (128 bytes) for i.MX51.

Take into account that loading the kernel using a single word takes a
lot of time..

>> However, I am currently working on several issues for MX51. It should be
>> nice to know which are your plans to save both some time ;-)
> 
> Well, I am in a bit of a hurry, and essentially what I need is to be able to 
> access SPI-nor flash (spansion type) for environment and booting linux.
> MMC/SD access would be nice, but is not yet necessary.

Ok, quite the same. I have a ST flash, but we get the same problems, I see.

> I know. I thought to do it in two steps: Fix mxc_spi.c with a workaround for 
> the pmic driver (which amounts to '#define spi_xfer spi_xfer_fsl' at the 
> beginning of this driver basically) and fix the pmic driver later, since it is 
> probably not trivial, and needs to be done carefully (you know, one can smoke 
> a board by mistake :-)

I know, this makes funny setting voltages via software....

Best regards,
Stefano

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