Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 12 Jan 2023 12:43:46 -0600 | Subject | Re: [PATCH 2/2] regmap: sdw: Remove 8-bit value size restriction | From | Pierre-Louis Bossart <> |
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On 1/12/23 12:14, Mark Brown wrote: > On Thu, Jan 12, 2023 at 11:38:38AM -0600, Pierre-Louis Bossart wrote: > >>> +static int regmap_sdw_gather_write(void *context, >>> + const void *reg_buf, size_t reg_size, >>> + const void *val_buf, size_t val_size) >>> { >>> struct device *dev = context; >>> struct sdw_slave *slave = dev_to_sdw_dev(dev); >>> - int read; >>> + u32 addr = le32_to_cpu(*(const __le32 *)reg_buf); > >> what's the difference between regmap_sdw_write() and >> regmap_sdw_gather_write()? Seems to me that it's the same functionality >> of writing at consecutive addresses. It's not a true 'gather' in the >> sense that only the first address is used? > > The regmap gather_write() operation allows the bus to take two buffers, > one for the register and one for the value, rather than requiring the > core combine everything into a single buffer (mainly useful for large > transfers like firmware downloads).
Right, but that's not supported in SoundWire. sdw_nwrite() will only work with consecutive addresses - and the auto-increment is handled in software, not hardware.
What's suggested here is to use the first element of reg_buf, which begs the question how different this is from a regular write. If there was a discontinuity in reg_buf then this wouldn't work at all.
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