2011/10/24, Giuseppe CAVALLARO <peppe.cavallaro@xxxxxx>: > On 10/24/2011 4:05 PM, Kelvin Cheung wrote: >> 2011/10/24, Giuseppe CAVALLARO <peppe.cavallaro@xxxxxx>: >>> Hello Kelvin. >>> >>> On 10/24/2011 12:36 PM, Kelvin Cheung wrote: >>> >>> [snip] >>> >>>> According to datasheet of Loongson 1B, the buffer size in RX/TX >>>> descriptor is only 2KB. So the Loongson1B's GMAC could not handle >>>> jumbo frames. And the second buffer is useless in this case. Am I >>>> right? Is there a better way than ifdef CONFIG_MACH_LOONGSON1 to >>>> avoid duplicate code? >>> >>> Sorry for my misunderstanding. >>> >>> I think you have to use the normal descriptor and remove the enh_desc >>> from the platform w/o modifying the driver at all. >>> >>> The driver will be able to select/configure all automatically (also >>> jumbo). >>> >>> Let me know. >> >> That's the problem. >> The bitfield definition of Loongson1B is also different from normal >> descriptor. > > The problem is not in the Loongson1B gmac. I found that the bit checksum_insertion is not existed in normal descriptor. > The normal descriptor fields in the stmmac refer to an old synopsys > databook. Could you send me the new databook of Synopsys GMAC? > New chips have the same structure you have added; so we should fix this > in the driver w/o breaking the compatibility for old chips. Agree. > I kindly ask you to confirm if the currently normal descriptor structure > (w/o your changes) doesn't work on your platform. > Did you test it? Well, the normal descriptor works on my platform except TX checksum offload. >> Moreover, I want to enable the TX checksum offload function which is >> not supported in normal descriptor. >> Any suggestions? > > It is supported but you have to pass from the platform: tx_coe = 1. I noticed that the flag csum_insertion is passed to ndesc_prepare_tx_desc() in stmmac_xmit(). But ndesc_prepare_tx_desc() just ignores it. In other words, the TX checksum offload function is disabled in normal descriptor currently. Should we fix this problem for normal descriptor? > Peppe >> >>> Note: >>> IIRC, there is a bit difference in case of normal descriptors for >>> Synopsys databook newer than the 1.91 (I used for testing this mode). >>> In any case, I remember that, on some platforms, the normal descriptors >>> have been used w/o problems also on these new chip generations. >>> >>> Peppe >>> >>> >> >> > > -- Best Regards! Kelvin
