SPI controller hangs in 2.6 and not in 2.4 (on MPC875)

Hi Melinda,

the problem in my case was caused by the following instructions to allocate the buffers for SPI controller tx and rx:

        rxbuffer = (u8*)m8xx_cpm_hostalloc(SPI_MAX_BUFFER_SIZE);  
        txbuffer = (u8*)m8xx_cpm_hostalloc(SPI_MAX_BUFFER_SIZE); 
        // Set the bd's rx and tx buffer address pointers
        rbdf->cbd_bufaddr = virt_to_bus((void *)rxbuffer);                                 
        tbdf->cbd_bufaddr = virt_to_bus((void *)txbuffer);   

I don't know why (I'm asking an opinion to Vitaly Bordug), I replaced the allocation of rx and tx buffers with:

...->cbd_bufaddr = __pa(__get_free_page(GFP_KERNEL | GFP_DMA))

but it will better to use dma_alloc_coherent.
In my case the use of m8xx_cpm_hostalloc led to an immediate kernel hang after giving the start command to the spi controller.

Bye,
Antonio.


                             

On Sun, 25 Feb 2007 20:51:12 +0100
DI BACCO ANTONIO - technolabs wrote:

Hi Melinda,

the problem in my case was caused by the following instructions to
allocate the buffers for SPI controller tx and rx:

        rxbuffer = (u8*)m8xx_cpm_hostalloc(SPI_MAX_BUFFER_SIZE);  
        txbuffer = (u8*)m8xx_cpm_hostalloc(SPI_MAX_BUFFER_SIZE); 
        // Set the bd's rx and tx buffer address pointers
        rbdf->cbd_bufaddr = virt_to_bus((void
*)rxbuffer); tbdf->cbd_bufaddr = virt_to_bus((void *)txbuffer);   

I don't know why (I'm asking an opinion to Vitaly Bordug), I replaced
the allocation of rx and tx buffers with:

...->cbd_bufaddr = __pa(__get_free_page(GFP_KERNEL | GFP_DMA))

Well this is just evil... even if it works :)

but it will better to use dma_alloc_coherent.
In my case the use of m8xx_cpm_hostalloc led to an immediate kernel
hang after giving the start command to the spi controller.

Heh, this case you'lll have to use dpram for the buffers I guess iiuc.

dma_* stuff might work too but I'm not sure. Moreover, it didn't work  for 
me in case of powerpc, where m8xx_cpm_hostalloc made as a placeholder for 
dma_alloc_coherent...