From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@bootlin.com (Maxime Ripard) Date: Tue, 27 Feb 2018 10:09:13 +0100 Subject: [PATCH v4] rtc: ac100: Fix ac100 determine rate bug In-Reply-To: <20180226211901.9805-1-embed3d@gmail.com> References: <20180226211901.9805-1-embed3d@gmail.com> Message-ID: <20180227090913.3vb6yudd4nh2wlyh@flea> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Feb 26, 2018 at 10:19:01PM +0100, Philipp Rossak wrote: > This patch fixes a bug, that prevents the Allwinner A83T and the A80 > from a successful boot. > > The bug is there since v4.16-rc1 and appeared after the clk branch was > merged. > > You can find the shortend trace below: > > Unable to handle kernel NULL pointer dereference at virtual address > 00000000 > pgd = (ptrval) > [00000000] *pgd=00000000 > Internal error: Oops: 5 [#1] SMP ARM > Modules linked in: > CPU: 0 PID: 49 Comm: kworker/0:1 Not tainted 4.15.0-10190-gb89e32ccd1be #2 > Hardware name: Allwinner sun8i Family > Workqueue: events deferred_probe_work_func > PC is at clk_hw_get_rate+0x0/0x34 > LR is at ac100_clkout_determine_rate+0x48/0x19c > > [ ... ] > > (clk_hw_get_rate) from (ac100_clkout_determine_rate+0x48/0x19c) > (ac100_clkout_determine_rate) from (clk_core_set_rate_nolock+0x3c/0x1a0) > (clk_core_set_rate_nolock) from (clk_set_rate+0x30/0x88) > (clk_set_rate) from (of_clk_set_defaults+0x200/0x364) > (of_clk_set_defaults) from (platform_drv_probe+0x18/0xb0) > > To fix that bug, we first check if the return of the > clk_hw_get_parent_by_index is non zero. If it is zero we skip that > clock parent. > > The BUG report could be found here: https://lkml.org/lkml/2018/2/10/198 > > Fixes: 04940631b8d2 ("rtc: ac100: Add clk output support") > > Signed-off-by: Philipp Rossak Acked-by: Maxime Ripard Thanks! Maxime -- Maxime Ripard, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 833 bytes Desc: not available URL: