Re: [PATCH v2 15/29] net: designware: fix non-1:1 mapped 64-bit systems

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 21.06.21 09:25, Sascha Hauer wrote:
> On Sat, Jun 19, 2021 at 06:50:41AM +0200, Ahmad Fatoum wrote:
>> drivers/net/designware.c handles the older Designware < 4.x MAC IPs,
>> which do not support DMA beyond 32-bit. They are still being integrated
>> into SoCs with 64-bit CPUs like the StarFive JH7100, which additionally
>> needs a non 1:1 mapping for coherent DMA.
>>
>> Fix the driver to support such usage. The driver still has the assumption
>> that barebox core will only pass it 32-bit pointers. This is now made
>> explicit by returning error codes when the DMA mask is violated.
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> ---
>>  arch/riscv/include/asm/io.h | 10 +++++++
>>  drivers/net/designware.c    | 57 ++++++++++++++++++++++---------------
>>  drivers/net/designware.h    | 28 +++++++++++++++---
>>  3 files changed, 68 insertions(+), 27 deletions(-)
>>
>> diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
>> index 3cdea7fcace1..795e670e3b9b 100644
>> --- a/arch/riscv/include/asm/io.h
>> +++ b/arch/riscv/include/asm/io.h
>> @@ -5,4 +5,14 @@
>>  
>>  #include <asm-generic/io.h>
>>  
>> +static inline void *phys_to_virt(unsigned long phys)
>> +{
>> +	return (void *)phys;
>> +}
>> +
>> +static inline unsigned long virt_to_phys(volatile void *mem)
>> +{
>> +	return (unsigned long)mem;
>> +}
>> +
>>  #endif /* __ASM_RISCV_IO_H */
>> diff --git a/drivers/net/designware.c b/drivers/net/designware.c
>> index 0ee6d3d78ac7..559e202c29ce 100644
>> --- a/drivers/net/designware.c
>> +++ b/drivers/net/designware.c
>> @@ -104,15 +104,15 @@ static void tx_descs_init(struct eth_device *dev)
>>  {
>>  	struct dw_eth_dev *priv = dev->priv;
>>  	struct eth_dma_regs *dma_p = priv->dma_regs_p;
>> -	struct dmamacdescr *desc_table_p = &priv->tx_mac_descrtable[0];
>> +	struct dmamacdescr *desc_table_p = &priv->tx_mac_descrtable_cpu[0];
>>  	char *txbuffs = &priv->txbuffs[0];
>>  	struct dmamacdescr *desc_p;
>>  	u32 idx;
>>  
>>  	for (idx = 0; idx < CONFIG_TX_DESCR_NUM; idx++) {
>>  		desc_p = &desc_table_p[idx];
>> -		desc_p->dmamac_addr = &txbuffs[idx * CONFIG_ETH_BUFSIZE];
>> -		desc_p->dmamac_next = &desc_table_p[idx + 1];
>> +		desc_p->dmamac_addr = virt_to_phys(&txbuffs[idx * CONFIG_ETH_BUFSIZE]);
>> +		desc_p->dmamac_next = tx_dma_addr(priv, &desc_table_p[idx + 1]);
>>  
>>  		if (priv->enh_desc) {
>>  			desc_p->txrx_status &= ~(DESC_ENH_TXSTS_TXINT | DESC_ENH_TXSTS_TXLAST |
>> @@ -130,9 +130,9 @@ static void tx_descs_init(struct eth_device *dev)
>>  	}
>>  
>>  	/* Correcting the last pointer of the chain */
>> -	desc_p->dmamac_next = &desc_table_p[0];
>> +	desc_p->dmamac_next = tx_dma_addr(priv, &desc_table_p[0]);
>>  
>> -	writel((ulong)&desc_table_p[0], &dma_p->txdesclistaddr);
>> +	writel(desc_p->dmamac_next, &dma_p->txdesclistaddr);
>>  	priv->tx_currdescnum = 0;
>>  }
>>  
>> @@ -140,15 +140,15 @@ static void rx_descs_init(struct eth_device *dev)
>>  {
>>  	struct dw_eth_dev *priv = dev->priv;
>>  	struct eth_dma_regs *dma_p = priv->dma_regs_p;
>> -	struct dmamacdescr *desc_table_p = &priv->rx_mac_descrtable[0];
>> +	struct dmamacdescr *desc_table_p = &priv->rx_mac_descrtable_cpu[0];
>>  	char *rxbuffs = &priv->rxbuffs[0];
>>  	struct dmamacdescr *desc_p;
>>  	u32 idx;
>>  
>>  	for (idx = 0; idx < CONFIG_RX_DESCR_NUM; idx++) {
>>  		desc_p = &desc_table_p[idx];
>> -		desc_p->dmamac_addr = &rxbuffs[idx * CONFIG_ETH_BUFSIZE];
>> -		desc_p->dmamac_next = &desc_table_p[idx + 1];
>> +		desc_p->dmamac_addr = virt_to_phys(&rxbuffs[idx * CONFIG_ETH_BUFSIZE]);
> 
> You have both the DMA and virtual addresses available when allocating
> the memory. I think you should use this information rather than
> introducing the need for a virt_to_phys() phys_to_virt() pair.

desc_p points at DMA coherent memory. desc_p->dmamac_addr is supposed to contain
the physical address of memory used for streaming DMA. I think virt_to_phys
is appropriate here.

> 
>> @@ -276,7 +276,7 @@ static int dwc_ether_send(struct eth_device *dev, void *packet, int length)
>>  	struct dw_eth_dev *priv = dev->priv;
>>  	struct eth_dma_regs *dma_p = priv->dma_regs_p;
>>  	u32 owndma, desc_num = priv->tx_currdescnum;
>> -	struct dmamacdescr *desc_p = &priv->tx_mac_descrtable[desc_num];
>> +	struct dmamacdescr *desc_p = &priv->tx_mac_descrtable_cpu[desc_num];
>>  
>>  	owndma = priv->enh_desc ? DESC_ENH_TXSTS_OWNBYDMA : DESC_TXSTS_OWNBYDMA;
>>  	/* Check if the descriptor is owned by CPU */
>> @@ -285,8 +285,8 @@ static int dwc_ether_send(struct eth_device *dev, void *packet, int length)
>>  		return -1;
>>  	}
>>  
>> -	memcpy((void *)desc_p->dmamac_addr, packet, length);
>> -	dma_sync_single_for_device((unsigned long)desc_p->dmamac_addr, length,
>> +	memcpy(dmamac_addr(desc_p), packet, length);
>> +	dma_sync_single_for_device(desc_p->dmamac_addr, length,
>>  				   DMA_TO_DEVICE);
> 
> Rather use dma_map_single() here?

There's is an unbalanced dma_sync_single_for_cpu in rx_descs_init().
I wasn't sure how to deal with it, had I wanted to move everything to dma_map_single.

I can supply a patch later for dma_map_single(), once I am told how, if that's
ok with you.

> 
> Sascha
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox