| Message ID | 20210507004047.4454-1-chris.packham@alliedtelesis.co.nz |
|---|---|
| Headers | show |
| Series | P2040/P2041 i2c recovery erratum | expand |
On Fri, 2021-05-07 at 12:40 +1200, Chris Packham wrote: > The i2c controllers on the P2040/P2041 have an erratum where the > documented scheme for i2c bus recovery will not work (A-004447). A > different mechanism is needed which is documented in the P2040 Chip > Errata Rev Q (latest available at the time of writing). From what I can tell this Erratum also applies to P1010 Jocke
On Fri, 2021-05-07 at 10:04 +0200, Joakim Tjernlund wrote: > On Fri, 2021-05-07 at 12:40 +1200, Chris Packham wrote: > > The i2c controllers on the P2040/P2041 have an erratum where the > > documented scheme for i2c bus recovery will not work (A-004447). A > > different mechanism is needed which is documented in the P2040 Chip > > Errata Rev Q (latest available at the time of writing). > > From what I can tell this Erratum also applies to P1010 > > Jocke Reference: https://media.digikey.com/pdf/PCNs/Freescale/P1010CE_RevL.pdf Also, I think this series should go to stable. Jocke
On Fri, May 7, 2021 at 3:40 AM Chris Packham <chris.packham@alliedtelesis.co.nz> wrote: > > The P2040/P2041 has an erratum where the normal i2c recovery mechanism > does not work. Implement the alternative recovery mechanism documented > in the P2040 Chip Errata Rev Q. Thanks. > +static int i2c_mpc_wait_sr(struct mpc_i2c *i2c, int mask) > +{ > + int ret; > + u8 val; > + > + ret = readb_poll_timeout(i2c->base + MPC_I2C_SR, val, > + val & mask, 0, 100); > + > + return ret; > +} So, now you may shrink it even further, i.e. void __iomem *sr = i2c->base + MPC_I2C_SR; u8 val; return readb_poll_timeout(sr, val, val & mask, 0, 100);
On Fri, 2021-05-07 at 14:46 +0300, Andy Shevchenko wrote: > On Fri, May 7, 2021 at 3:40 AM Chris Packham > <chris.packham@alliedtelesis.co.nz> wrote: > > > > The P2040/P2041 has an erratum where the normal i2c recovery mechanism > > does not work. Implement the alternative recovery mechanism documented > > in the P2040 Chip Errata Rev Q. > > Thanks. > > > +static int i2c_mpc_wait_sr(struct mpc_i2c *i2c, int mask) > > +{ > > + int ret; > > + u8 val; > > + > > + ret = readb_poll_timeout(i2c->base + MPC_I2C_SR, val, > > + val & mask, 0, 100); > > + > > + return ret; > > +} > > So, now you may shrink it even further, i.e. > > void __iomem *sr = i2c->base + MPC_I2C_SR; > u8 val; > > return readb_poll_timeout(sr, val, val & mask, 0, 100); > val looks uninitialised before use?
On Fri, May 7, 2021 at 5:52 PM Joakim Tjernlund <Joakim.Tjernlund@infinera.com> wrote: > On Fri, 2021-05-07 at 14:46 +0300, Andy Shevchenko wrote: > > On Fri, May 7, 2021 at 3:40 AM Chris Packham > > <chris.packham@alliedtelesis.co.nz> wrote: ... > > So, now you may shrink it even further, i.e. > > > > void __iomem *sr = i2c->base + MPC_I2C_SR; > > u8 val; > > > > return readb_poll_timeout(sr, val, val & mask, 0, 100); > > > > val looks uninitialised before use? Nope. Thinking about naming, perhaps void __iomem *addr = i2c->base + MPC_I2C_SR; u8 sr; // or leave as val? return readb_poll_timeout(addr, sr, sr & mask, 0, 100); would be more clear.
On 7/05/21 8:24 pm, Joakim Tjernlund wrote: > On Fri, 2021-05-07 at 10:04 +0200, Joakim Tjernlund wrote: >> On Fri, 2021-05-07 at 12:40 +1200, Chris Packham wrote: >>> The i2c controllers on the P2040/P2041 have an erratum where the >>> documented scheme for i2c bus recovery will not work (A-004447). A >>> different mechanism is needed which is documented in the P2040 Chip >>> Errata Rev Q (latest available at the time of writing). >> From what I can tell this Erratum also applies to P1010 Will add for v3. >> Jocke > Reference: https://media.digikey.com/pdf/PCNs/Freescale/P1010CE_RevL.pdf > > Also, I think this series should go to stable. This series builds on changes that have been merged for v5.13. I haven't checked if it applies to stable, I think at least commit 65171b2df15e ("i2c: mpc: Make use of i2c_recover_bus()") would need to come along with it.
The P2040/P2041 has an erratum where the i2c recovery scheme documented in the reference manual (and currently implemented in the i2c-mpc.c driver) does not work. The errata document provides an alternative that does work. This series implements that alternative and uses a property in the devicetree to decide when the alternative mechanism is needed. Chris Packham (3): dt-bindings: i2c: mpc: Add fsl,i2c-erratum-a004447 flag powerpc/fsl: set fsl,i2c-erratum-a004447 flag for P2041 i2c controllers i2c: mpc: implement erratum A-004447 workaround .../devicetree/bindings/i2c/i2c-mpc.yaml | 7 ++ arch/powerpc/boot/dts/fsl/p2041si-post.dtsi | 16 ++++ drivers/i2c/busses/i2c-mpc.c | 84 ++++++++++++++++++- 3 files changed, 105 insertions(+), 2 deletions(-)