Re: [PATCH 1/5] mmc: renesas_sdhi_internal_dmac: limit DMA RX for old SoCs

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> > +static unsigned long global_flags;
> 
> Is the restriction on concurrent DMA RX streams global or per-device?

? Each device has only one DMA RX channel. Hey Simon, you upstreamed
this driver :) Or did I get the question wrong?

> > +	if (dir == DMA_FROM_DEVICE)
> > +		clear_bit(SDHI_INTERNAL_DMAC_RX_IN_USE, &global_flags);
> > +
> 
> Is clear_bit() expensive? If so it might be worth avoiding on SoCs that
> don't have the restriction covered by this patch.

It's an atoimc bitop, so maybe has a memory barrier. Hmm, the above
version is better on the cache lines, though, if you don't have the
restriction.

Will think about it and make sure both clear_bit() are in sync.

Attachment: signature.asc
Description: PGP signature


[Index of Archives]     [Linux Samsung SOC]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Device Mapper]

  Powered by Linux