On 06/11/2014 09:25 AM, Peter De Schrijver wrote: > On Wed, Jun 11, 2014 at 02:47:31PM +0200, Mikko Perttunen wrote: >> On 05/06/14 16:09, Peter De Schrijver wrote: >> ... >>> +int tegra_fuse_readl(u32 offset, u32 *val) >>> +{ >>> + if (!fuse_readl) >>> + return -ENXIO; >>> + >>> + *val = fuse_readl(offset); >>> + >>> + return 0; >>> +} >>> + >> >> -EPROBE_DEFER would be a better error value, so that drivers can work > > Ok. > >> even if they are initially probed before the fuse driver. Of course, if >> the fuse initialization is moved into machine init then this is a non-issue. > > The exported function will always be initialized later because on Tegra20 it > requires APB DMA to be available. If you read the fuses directly, the system > sometimes hangs. That's not true in the current code. IIRC, the bug was that *if* an APB DMA access to anything and a CPU access to the fuses happen at the same time, then there can be a hang. As such, the current fuse code accesses the fuses directly (without potential for a hang) if the APB DMA driver is not available, but once the driver becomes available, it reads the fuses through DMA instead. Does the new code not do that? -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html