On Tue, Nov 11, 2014 at 07:10:33PM +0100, Juergen Borleis wrote: > Hi, > > the S3C2410 NAND driver [1] can still be used for NANDs attached to an S3C6410 > SoC. But this driver has a "nice" feature called "clock off" to save some > power while not in use. I tried it here on my Mini6410 platform and it freezes > the system. > > The clock tree is somehow: > > [...] > hclk 4 4 133000000 0 0 > hclk_mfc 0 0 133000000 0 0 > hclk_mem0 2 2 133000000 0 0 > mem0_srom 0 0 133000000 0 0 > mem0_nfcon 1 1 133000000 0 0 > mem0_onenand0 0 0 133000000 0 0 > mem0_onenand1 0 0 133000000 0 0 > mem0_cfcon 0 0 133000000 0 0 > [...] > > On the Mini6410 the "mem0_nfcon" clock is the only single user of the > "hclk_mem0". And this clock is required to keep the access to the external > network device enabled. When the NAND driver disables its clock "mem0_nfcon", > the "hclk_mem0" gets also disabled because there is no consumer anymore. The > next time the network driver tries to access its device, the SoC freezes. Sounds like the network driver should hold a reference to hclk_mem0. I assume the system uses a device tree? This is the dm9000 driver? It doesn't seem to use clk stuff, but it should be possible to add an optional clk entry. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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