| Message ID | 20230307164405.14218-4-johan+linaro@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | serial: qcom-geni: fix console shutdown hang | expand |
Hi, On Tue, Mar 7, 2023 at 8:43 AM Johan Hovold <johan+linaro@kernel.org> wrote: > > Make sure that there is data in the ring buffer before trying to set up > a zero-length DMA transfer. > > This specifically fixes the following warning when unmapping the empty > buffer on the sc8280xp-crd: > > WARNING: CPU: 0 PID: 138 at drivers/iommu/dma-iommu.c:1046 iommu_dma_unmap_page+0xbc/0xd8 > ... > Call trace: > iommu_dma_unmap_page+0xbc/0xd8 > dma_unmap_page_attrs+0x30/0x1c8 > geni_se_tx_dma_unprep+0x28/0x38 > qcom_geni_serial_isr+0x358/0x75c > > Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA") > Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > --- > drivers/tty/serial/qcom_geni_serial.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c > index 2aa3872e6283..9871225b2f9b 100644 > --- a/drivers/tty/serial/qcom_geni_serial.c > +++ b/drivers/tty/serial/qcom_geni_serial.c > @@ -631,6 +631,9 @@ static void qcom_geni_serial_start_tx_dma(struct uart_port *uport) > if (port->tx_dma_addr) > return; > > + if (uart_circ_empty(xmit)) > + return; I guess you could remove the uart_circ_empty() test in qcom_geni_serial_handle_tx_dma() now? In any case, with or without that: Reviewed-by: Douglas Anderson <dianders@chromium.org>
On Tue, Mar 07, 2023 at 10:41:46AM -0800, Doug Anderson wrote: > Hi, > > On Tue, Mar 7, 2023 at 8:43 AM Johan Hovold <johan+linaro@kernel.org> wrote: > > > > Make sure that there is data in the ring buffer before trying to set up > > a zero-length DMA transfer. > > > > This specifically fixes the following warning when unmapping the empty > > buffer on the sc8280xp-crd: > > > > WARNING: CPU: 0 PID: 138 at drivers/iommu/dma-iommu.c:1046 iommu_dma_unmap_page+0xbc/0xd8 > > ... > > Call trace: > > iommu_dma_unmap_page+0xbc/0xd8 > > dma_unmap_page_attrs+0x30/0x1c8 > > geni_se_tx_dma_unprep+0x28/0x38 > > qcom_geni_serial_isr+0x358/0x75c > > > > Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA") > > Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > > --- > > drivers/tty/serial/qcom_geni_serial.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c > > index 2aa3872e6283..9871225b2f9b 100644 > > --- a/drivers/tty/serial/qcom_geni_serial.c > > +++ b/drivers/tty/serial/qcom_geni_serial.c > > @@ -631,6 +631,9 @@ static void qcom_geni_serial_start_tx_dma(struct uart_port *uport) > > if (port->tx_dma_addr) > > return; > > > > + if (uart_circ_empty(xmit)) > > + return; > > I guess you could remove the uart_circ_empty() test in > qcom_geni_serial_handle_tx_dma() now? I considered that, but decided to leave it in as it makes the flow in qcom_geni_serial_handle_tx_dma() a bit more obvious (and that function already handles the related uart_write_wakeup() which the check could potentially be combined with). > In any case, with or without that: > > Reviewed-by: Douglas Anderson <dianders@chromium.org> Thanks for reviewing. Johan
diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index 2aa3872e6283..9871225b2f9b 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -631,6 +631,9 @@ static void qcom_geni_serial_start_tx_dma(struct uart_port *uport) if (port->tx_dma_addr) return; + if (uart_circ_empty(xmit)) + return; + xmit_size = uart_circ_chars_pending(xmit); if (xmit_size < WAKEUP_CHARS) uart_write_wakeup(uport);
Make sure that there is data in the ring buffer before trying to set up a zero-length DMA transfer. This specifically fixes the following warning when unmapping the empty buffer on the sc8280xp-crd: WARNING: CPU: 0 PID: 138 at drivers/iommu/dma-iommu.c:1046 iommu_dma_unmap_page+0xbc/0xd8 ... Call trace: iommu_dma_unmap_page+0xbc/0xd8 dma_unmap_page_attrs+0x30/0x1c8 geni_se_tx_dma_unprep+0x28/0x38 qcom_geni_serial_isr+0x358/0x75c Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA") Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> Signed-off-by: Johan Hovold <johan+linaro@kernel.org> --- drivers/tty/serial/qcom_geni_serial.c | 3 +++ 1 file changed, 3 insertions(+)