Subject: Re: [PATCH] powerpc: Add DMA mask to MPSC serial and network and UART device to serial

From: Benjamin Herrenschmidt <[email-masked]>
Date: Mon, 01 Feb 2010 15:58:33 +1100

On Fri, 2010-01-29 at 18:04 -0600, Corey Minyard wrote:
> From: Corey Minyard <[email-masked]>
> 
> The MPSC drivers that use DMA need to set coherent_dma_mask to allow
> dma_alloc_xxx routines to work properly.  Also, the mpsc serial driver
> needed to set pi->port.dev to register properly.  With these fixes,
> the MPSC drivers seem to work again.
> 
> Signed-off-by: Corey Minyard <[email-masked]>
> ---

Is that enough ? Since 2.6.31 we also need the dma ops to be filled
properly and obviously that isn't going to happen for random platform
devices... Or are those initialized elsewhere by your platform code ? In
which case it might be a good place to also set the coherent mask...

Maybe we should have a more generic way to set the "default" dma
information (including ops, masks etc...) for use by platform,
of_platform etc... devices.

Cheers,
Ben.

> I'm not really sure about where to set the coherent_dma_mask, it seems
> like a more general place would be better but I couldn't find it.
> 
> Without these, the console stops working after the switchover and
> the network driver fails to allocate buffers.  With these, my board
> boots up and works fine.
> 
> Index: linux-2.6.31/drivers/serial/mpsc.c
> ===================================================================
> --- linux-2.6.31.orig/drivers/serial/mpsc.c
> +++ linux-2.6.31/drivers/serial/mpsc.c
> @@ -2071,6 +2071,9 @@ static int mpsc_drv_probe(struct platfor
>  		if (!(rc = mpsc_drv_map_regs(pi, dev))) {
>  			mpsc_drv_get_platform_data(pi, dev, dev->id);
>  
> +			dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> +			pi->port.dev = &dev->dev;
> +
>  			if (!(rc = mpsc_make_ready(pi))) {
>  				spin_lock_init(&pi->tx_lock);
>  				if (!(rc = uart_add_one_port(&mpsc_reg,
> Index: linux-2.6.31/drivers/net/mv643xx_eth.c
> ===================================================================
> --- linux-2.6.31.orig/drivers/net/mv643xx_eth.c
> +++ linux-2.6.31/drivers/net/mv643xx_eth.c
> @@ -2916,7 +2916,7 @@ static int mv643xx_eth_probe(struct plat
>  	mp->shared = platform_get_drvdata(pd->shared);
>  	mp->base = mp->shared->base + 0x0400 + (pd->port_number << 10);
>  	mp->port_num = pd->port_number;
> -
> +	pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
>  	mp->dev = dev;
>  
>  	set_params(mp, pd);
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