[ Trimming recipients list for idle chat ]
On 05/09/2019 09:52, Lee Jones wrote:
> 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.
>
> The beautiful thing about this approach is that, *if* the Geni SE DMA
> ever starts working, we can remove the C code and any old properties
> left in older DTs just become NOOP. Older kernels with newer DTs (less
> of a priority) *still* will not work - but they do not work now anyway.
>
> Fixes: 8bc529b25354 ("soc: qcom: geni: Add support for ACPI")
> Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
> Reviewed-by: Vinod Koul <vkoul@xxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-qcom-geni.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index a89bfce5388e..8822dea82980 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -353,13 +353,16 @@ static void geni_i2c_tx_fsm_rst(struct geni_i2c_dev *gi2c)
> static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
> u32 m_param)
> {
> + struct device_node *np = gi2c->se.dev->of_node;
> 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_property_read_bool(np, "qcom,geni-se-no-dma"))
> + dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
> +
> if (dma_buf)
> geni_se_select_mode(se, GENI_SE_DMA);
> else
> @@ -392,13 +395,16 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
> static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
> u32 m_param)
> {
> + struct device_node *np = gi2c->se.dev->of_node;
> 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_property_read_bool(np, "qcom,geni-se-no-dma"))
> + dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
> +
> if (dma_buf)
> geni_se_select_mode(se, GENI_SE_DMA);
> else
>
Would it make sense to factorize the DT lookup within a helper?
(For example; not compile-tested; not sure it's worth it)
diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index a89bfce5388e..1489181f60fe 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -350,6 +350,14 @@ static void geni_i2c_tx_fsm_rst(struct geni_i2c_dev *gi2c)
dev_err(gi2c->se.dev, "Timeout resetting TX_FSM\n");
}
+static void *get_dma_buf(struct geni_se *se, struct i2c_msg *msg)
+{
+ if (of_property_read_bool(se->dev->of_node, "qcom,geni-se-no-dma"))
+ return NULL;
+
+ return i2c_get_dma_safe_msg_buf(msg, 32);
+}
+
static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
u32 m_param)
{
@@ -359,7 +367,7 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
struct geni_se *se = &gi2c->se;
size_t len = msg->len;
- dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
+ dma_buf = get_dma_buf(se, msg);
if (dma_buf)
geni_se_select_mode(se, GENI_SE_DMA);
else
@@ -398,7 +406,7 @@ static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
struct geni_se *se = &gi2c->se;
size_t len = msg->len;
- dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
+ dma_buf = get_dma_buf(se, msg);
if (dma_buf)
geni_se_select_mode(se, GENI_SE_DMA);
else
