Hi Tim, On Tue, 16 Aug 2022 at 13:50, Tim Harvey <thar...@gateworks.com> wrote: > > On Mon, Aug 15, 2022 at 3:16 PM Simon Glass <s...@chromium.org> wrote: > > > > Hi Tim, > > > > On Mon, 15 Aug 2022 at 11:48, Tim Harvey <thar...@gateworks.com> wrote: > > > > > > On Sat, Aug 13, 2022 at 7:59 AM Simon Glass <s...@chromium.org> wrote: > > > > > > > > Hi Tim, > > > > > > > > On Thu, 11 Aug 2022 at 11:57, Tim Harvey <thar...@gateworks.com> wrote: > > > > > > > > > > According to the comment block "The default {addr} parameter is one > > > > > byte > > > > > (.1) which works well for memories and registers with 8 bits of > > > > > address > > > > > space." > > > > > > > > > > While this is true for legacy I2C a default length of -1 is being > > > > > passed > > > > > for DM_I2C which results in a usage error. > > > > > > > > > > Restore the documented behavior by always using a default alen of 1. > > > > > > > > > > Signed-off-by: Tim Harvey <thar...@gateworks.com> > > > > > > > > > > This is an RFC as I'm unclear if we want to restore the legacy usage > > > > > or > > > > > enforce a new usage (in which case the comment block should be > > > > > updated) > > > > > and I'm not clear if this is documented in other places. If the > > > > > decision > > > > > is to enforce a new usage then it is unclear to me how to specifiy the > > > > > default alen as there is no command for that (i2c alen [len]?). > > > > > --- > > > > > cmd/i2c.c | 10 ---------- > > > > > 1 file changed, 10 deletions(-) > > > > > > > > > > > > > Can you dig into this a little more on your board? DEFAULT_ADDR_LEN is > > > > set to -1 so that by default it does not get set by the command, and > > > > the existing alen is used. > > > > > > > > This is necessary for driver model, since the alen can be set by the > > > > peripheral device and we don't want to overwrite it: > > > > > > > > if (!ret && alen != -1) > > > > ret = i2c_set_chip_offset_len(dev, alen); > > > > > > > > > > Simon, > > > > > > Here's some annotated debug prints added where chip_offset is passed/set: > > > Model: Gateworks Venice GW73xx-0x i.MX8MM Development Kit > > > DRAM: 1 GiB > > > i2c_chip_of_to_plat gsc@20 offset_len=1 > > > i2c_chip_of_to_plat pmic@69 offset_len=1 > > > i2c_get_chip i2c@30a20000 0x51 offset_len=1 > > > i2c_bind_driver i2c@30a20000 offset_len=1 > > > i2c_set_chip_offset_len generic_51 offset_len=1 > > > dm_i2c_read generic_51 offset=0 offset_len=1 > > > i2c_setup_offset 0x51 offset=0 offset_len=1 > > > Core: 209 devices, 27 uclasses, devicetree: separate > > > ... > > > u-boot=> i2c dev 0 && i2c md 0x51 0 50 > > > Setting bus to 0 > > > i2c - I2C sub-system > > > > > > Usage: > > > i2c bus [muxtype:muxaddr:muxchannel] - show I2C bus info > > > ... > > > > > > So the chip I noticed this issue with is 0x51 which an atmel,24c02 > > > compatible eeprom which imx8mm-venice-gw700x.dtsi defines 4 of > > > (i2c1-0x50, i2c1-0x51, i2c1-0x52, i2c1-0x53). You can see above > > > i2c1-0x51 (i2c1=i2c@30a20000) is accessed early as it holds the board > > > model information and at that point in time it's accessed with alen=1 > > > (which I specify in board/gateworks/venice/eeprom.c:eeprom_read()) but > > > by the time the 'i2c md 0x51 0 50' comes around > > > i2c_get_chip_offset_len() returns 0 for this device. The other eeprom > > > devices on i2c1 are never accessed by a driver so they would never > > > have a 'default' alen set. > > > > OK I see, > > > > > > > > Where is the initial setting of alen supposed to have come? > > > > The "u-boot,i2c-offset-len" property in the device tree. > > > > Simon, > > I see what happened here. The issue is caused by commit 8f8c04bf1ebbd > ("i2c: fix stack buffer overflow vulnerability in i2c md command") > which changed alen from int to uint (yet its still getting set to > DEFAULT_ADDR_LEN which is -1) thus the 'if (alen > 3)' now returns > CMD_RET_USAGE. > > I'm not sure what the best fix is at this point - revert all or part > of 8f8c04bf1ebbd > > Nicolas, what is your opinion? To summarize commit 8f8c04bf1ebbd broke > the ability to pass a -1 default address length to do_i2c_* such that > something as common as 'i2c md 0x50 0 50' fails with a usage error.
Ah, ok. Well first we should add a test to dm/test/i2c.c to cover they failure you are seeing. Yes, revert part of it and then add checks for -ve values? Regards, Simon