From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: [RESEND v3 1/1] i2c: qcom-geni: Provide an option to disable DMA processing Date: Thu, 5 Sep 2019 15:41:22 +0100 Message-ID: <20190905144122.5689-1-lee.jones@linaro.org> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: alokc@codeaurora.org, agross@kernel.org, robh+dt@kernel.org, mark.rutland@arm.com, bjorn.andersson@linaro.org, vkoul@kernel.org, wsa@the-dreams.de Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, Lee Jones List-Id: linux-i2c@vger.kernel.org We have a production-level laptop (Lenovo Yoga C630) which is exhibiting a rather horrific bug. When I2C HID devices are being scanned for at boot-time the QCom Geni based I2C (Serial Engine) attempts to use DMA. When it does, the laptop reboots and the user never sees the OS. Signed-off-by: Lee Jones --- drivers/i2c/busses/i2c-qcom-geni.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c index a89bfce5388e..17abf60c94ae 100644 --- a/drivers/i2c/busses/i2c-qcom-geni.c +++ b/drivers/i2c/busses/i2c-qcom-geni.c @@ -355,11 +355,13 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg, { dma_addr_t rx_dma; unsigned long time_left; - void *dma_buf; + void *dma_buf = NULL; struct geni_se *se = &gi2c->se; size_t len = msg->len; - dma_buf = i2c_get_dma_safe_msg_buf(msg, 32); + if (!of_machine_is_compatible("lenovo,yoga-c630")) + dma_buf = i2c_get_dma_safe_msg_buf(msg, 32); + if (dma_buf) geni_se_select_mode(se, GENI_SE_DMA); else @@ -394,11 +396,13 @@ static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg, { dma_addr_t tx_dma; unsigned long time_left; - void *dma_buf; + void *dma_buf = NULL; struct geni_se *se = &gi2c->se; size_t len = msg->len; - dma_buf = i2c_get_dma_safe_msg_buf(msg, 32); + if (!of_machine_is_compatible("lenovo,yoga-c630")) + dma_buf = i2c_get_dma_safe_msg_buf(msg, 32); + if (dma_buf) geni_se_select_mode(se, GENI_SE_DMA); else -- 2.17.1