From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH v2 1/2] i2c: i2c-qcom-geni: Properly handle DMA safe buffers Date: Tue, 25 Sep 2018 00:13:04 +0200 Message-ID: <20180924221304.GF18592@kunai> References: <20180920180323.217377-1-swboyd@chromium.org> <20180920180323.217377-2-swboyd@chromium.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="4VrXvz3cwkc87Wze" Return-path: Content-Disposition: inline In-Reply-To: <20180920180323.217377-2-swboyd@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: Stephen Boyd Cc: linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, linux-arm-msm@vger.kernel.org, Karthikeyan Ramasubramanian , Sagar Dharia , Girish Mahadevan List-Id: linux-i2c@vger.kernel.org --4VrXvz3cwkc87Wze Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Sep 20, 2018 at 11:03:22AM -0700, Stephen Boyd wrote: > We shouldn't attempt to DMA map the message buffers passed into this > driver from the i2c core unless the message we're mapping have been > properly setup for DMA. The i2c core indicates such a situation by > setting the I2C_M_DMA_SAFE flag, so check for that flag before using DMA > mode. We can also bounce the buffer if it isn't already mapped properly > by using the i2c_get_dma_safe_msg_buf() APIs, so do that when we > want to use DMA for a message. >=20 > This fixes a problem where the kernel oopses cleaning pages for a buffer > that's mapped into the vmalloc space. The pages are returned from > request_firmware() and passed down directly to the i2c master to write > to the i2c touchscreen device. Mapping vmalloc buffers with > dma_map_single() won't work reliably, causing an oops like below: >=20 > Unable to handle kernel paging request at virtual address ffffffc01391d0= 00 > Mem abort info: > Exception class =3D DABT (current EL), IL =3D 32 bits > SET =3D 0, FnV =3D 0 > EA =3D 0, S1PTW =3D 0 > Data abort info: > ISV =3D 0, ISS =3D 0x00000146 > CM =3D 1, WnR =3D 1 > swapper pgtable: 4k pages, 39-bit VAs, pgd =3D ffffff8009ecf000 > [ffffffc01391d000] *pgd=3D000000017fffa803, *pud=3D000000017fffa803, *pm= d=3D0000000000000000 > Internal error: Oops: 96000146 [#1] PREEMPT SMP > Modules linked in: i2c_dev rfcomm uinput lzo lzo_compress hci_uart zram = btqca qcom_q6v5_pil bluetooth ecdh_generic qcom_common bridge qcom_q6v5 stp= llc ipt_MASQUERADE nf_nat_masquerade_ipv4 xt_mark fuse snd_seq_dummy snd_s= eq snd_seq_device cfg80211 rmtfs_mem smsc95xx usbnet mii joydev > CPU: 0 PID: 1269 Comm: bash Not tainted 4.14.68 #1 > task: ffffffc0dc2a0080 task.stack: ffffff800f978000 > PC is at __clean_dcache_area_poc+0x20/0x38 > LR is at __swiotlb_map_page+0x80/0x98 > pc : [] lr : [] pstate: 80400149 > sp : ffffff800f97ba20 > x29: ffffff800f97ba50 x28: 0000000000000001 > x27: ffffff8008a04000 x26: ffffffc0f79a7a28 > x25: 0000000000000000 x24: ffffffbf004e4740 > x23: 0000000000000000 x22: ffffffc0f94eb290 > x21: 000000009391d000 x20: 0000000000000084 > x19: 0000000000000001 x18: 0000000000000000 > x17: 0000000000000000 x16: ffffffc0dc2a0080 > x15: 0000000000000000 x14: 0000000000000001 > x13: 00000000000c00b1 x12: 0000000000000000 > x11: 0000000002000000 x10: 0000000000000000 > x9 : 0000000080000000 x8 : 000000001391d000 > x7 : ffffff80085649dc x6 : 0000000000000000 > x5 : 0000000000000000 x4 : 0000000000000001 > x3 : 000000000000003f x2 : 0000000000000040 > x1 : ffffffc01391d084 x0 : ffffffc01391d000 > Process bash (pid: 1269, stack limit =3D 0xffffff800f978000) > Call trace: > Exception stack(0xffffff800f97b8e0 to 0xffffff800f97ba20) > b8e0: ffffffc01391d000 ffffffc01391d084 0000000000000040 000000000000003f > b900: 0000000000000001 0000000000000000 0000000000000000 ffffff80085649dc > b920: 000000001391d000 0000000080000000 0000000000000000 0000000002000000 > b940: 0000000000000000 00000000000c00b1 0000000000000001 0000000000000000 > cros-ec-spi spi10.0: SPI transfer timed out > b960: ffffffc0dc2a0080 0000000000000000 0000000000000000 0000000000000001 > b980: 0000000000000084 000000009391d000 ffffffc0f94eb290 0000000000000000 > b9a0: ffffffbf004e4740 0000000000000000 ffffffc0f79a7a28 ffffff8008a04000 > b9c0: 0000000000000001 ffffff800f97ba50 ffffff800809a150 ffffff800f97ba20 > b9e0: ffffff800809bfb4 0000000080400149 ffffffc0f94eb290 0000000000000000 > ba00: 0000007fffffffff 0000000000000001 ffffff800f97ba50 ffffff800809bfb4 > [] __clean_dcache_area_poc+0x20/0x38 > [] geni_se_tx_dma_prep+0x80/0x154 > [] geni_i2c_xfer+0x14c/0x3dc > [] __i2c_transfer+0x428/0x83c > [] i2c_transfer+0x80/0xbc > [] i2c_master_send+0x5c/0x90 > [] elants_i2c_send+0x30/0x84 > [] write_update_fw+0x324/0x484 > [] dev_attr_store+0x40/0x58 > [] sysfs_kf_write+0x4c/0x64 > [] kernfs_fop_write+0x124/0x1bc > [] __vfs_write+0x54/0x14c > [] vfs_write+0xcc/0x188 > [] SyS_write+0x60/0xc0 > Exception stack(0xffffff800f97bec0 to 0xffffff800f97c000) > bec0: 0000000000000001 000000000e7ede70 0000000000000002 0000000000000000 > bee0: 0000000000000002 000000000e7ede70 00000000ec049bc8 0000000000000004 > bf00: 0000000000000002 0000000000000000 000000000e7f0f10 000000000ca2bcd8 > bf20: 0000000000000000 00000000ff9df69c 00000000ebfaf229 0000000000000000 > bf40: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > bf60: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > bf80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > bfa0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > bfc0: 00000000ebfec978 00000000400e0030 0000000000000001 0000000000000004 > bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [] el0_svc_naked+0x34/0x38 > Code: 9ac32042 8b010001 d1000443 8a230000 (d50b7a20) >=20 > Reported-by: Philip Chen > Cc: Karthikeyan Ramasubramanian > Cc: Sagar Dharia > Cc: Girish Mahadevan > Signed-off-by: Stephen Boyd Applied to for-current (with shortend BUG printout), thanks! 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