| Message ID | 20181030210917.32711-1-jae.hyun.yoo@linux.intel.com |
|---|---|
| Headers | show |
| Series | i2c: aspeed: Add bus idle waiting logic for multi-master use cases | expand |
On Tue, Oct 30, 2018 at 02:09:11PM -0700, Jae Hyun Yoo wrote: > In multi-master environment, this driver's master cannot know > exactly when a peer master sends data to this driver's slave so a > case can be happened that this master tries to send data through > the master_xfer function but slave data from peer master is still > being processed by this driver. To prevent state corruption in the > case, this patch adds checking code if any slave operation is > ongoing and it waits up to the bus timeout duration before starting > a master_xfer operation. > > To support this change, it introduces changes on i2c-core-base to > make that able to read the bus timeout and master transfer retries > count values from device tree properties. > > Please review this patch set. Marking this as "Changes requested". I think if the mutex approach works, these patches become obsolete then.
On 1/15/2019 2:47 PM, Wolfram Sang wrote: > On Tue, Oct 30, 2018 at 02:09:11PM -0700, Jae Hyun Yoo wrote: >> In multi-master environment, this driver's master cannot know >> exactly when a peer master sends data to this driver's slave so a >> case can be happened that this master tries to send data through >> the master_xfer function but slave data from peer master is still >> being processed by this driver. To prevent state corruption in the >> case, this patch adds checking code if any slave operation is >> ongoing and it waits up to the bus timeout duration before starting >> a master_xfer operation. >> >> To support this change, it introduces changes on i2c-core-base to >> make that able to read the bus timeout and master transfer retries >> count values from device tree properties. >> >> Please review this patch set. > > Marking this as "Changes requested". I think if the mutex approach > works, these patches become obsolete then. > Hi Wolfram, Thanks for your touching base. I made and tested a new patch in my local. Actually, I couldn't use a mutex because it should provide locking between driver context and interrupt context. Instead, after taking lots of experiments, I checked that idle waiting can be supported by this H/W so I didn't need to use any locking method in the driver code for multi-master handling. I'll submit a new patch tomorrow using a different thread. Please drop this patch set. Thanks, Jae
In multi-master environment, this driver's master cannot know exactly when a peer master sends data to this driver's slave so a case can be happened that this master tries to send data through the master_xfer function but slave data from peer master is still being processed by this driver. To prevent state corruption in the case, this patch adds checking code if any slave operation is ongoing and it waits up to the bus timeout duration before starting a master_xfer operation. To support this change, it introduces changes on i2c-core-base to make that able to read the bus timeout and master transfer retries count values from device tree properties. Please review this patch set. Thanks, -Jae Changes since v8: - Fixed a build break when CONFIG_I2C_SLAVE is not set. Changes since v7: - Simplified the bus idle waiting logic using jiffy based timer APIs. Changes since v6: - Changed the 'timeout-ms' property name to 'bus-timeout-ms'. Changes since v5: - Changed using of property reading API to device_property_read_u32. Changes since v4: - Moved the property reading code into i2c-base-core and changed the property name to 'timeout-ms'. Also, added '#retries' property reading code. - Changed bus busy checking logic to make that check slave_state instead of 'Transfer Mode State Machine' reg value. Changes since v3: - Changed the property name to 'timeout' and made it use the default setting in i2c-core when not specified. Changes since v2: - Changed the property name to 'aspeed,timeout' and made it to update the adapter's timeout configuration. Changes since v1: - Changed define names of timeout related. Jae Hyun Yoo (5): dt-bindings: i2c: Add 'bus-timeout-ms' and '#retries' properties as common optional i2c: core: Add support reading of 'bus-timeout-ms' and '#retries' properties dt-bindings: i2c: aspeed: Add 'bus-timeout-ms' property as an optional property i2c: aspeed: Remove hard-coded bus timeout value setting i2c: aspeed: Add bus idle waiting logic for multi-master use cases .../devicetree/bindings/i2c/i2c-aspeed.txt | 3 + Documentation/devicetree/bindings/i2c/i2c.txt | 6 ++ drivers/i2c/busses/i2c-aspeed.c | 56 +++++++++++++------ drivers/i2c/i2c-core-base.c | 12 +++- 4 files changed, 59 insertions(+), 18 deletions(-)