On Wednesday 12 November 2014 10:14:58 Uwe Kleine-König wrote: > Hello again, > > [extending audience a bit] > > On Tue, Nov 11, 2014 at 07:42:26PM +0100, Uwe Kleine-König wrote: > > 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. > > After talking to Jürgen by phone, the solution that the dm9000 driver > should handle the clock sounds wrong. The clk in question is needed by > the SoC to operate the bus the dm9000 is connected to. So I think the > right approach would include I think we need the same here for the S3C6410 SoC, like the imx-weim driver is for i.MX SoCs. jbe -- Pengutronix e.K. | Juergen Borleis | Industrial Linux Solutions | Phone: +49-5121-206917-5128 | Peiner Str. 6-8, 31137 Hildesheim, Germany | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
