Messages in this thread | | | From | Alexander Stein <> | Subject | Re: [PATCH 1/1] regmap: cache: downgrade log level for no cache defaults message | Date | Mon, 28 Nov 2022 15:58:40 +0100 |
| |
Hello Mark,
Am Freitag, 25. November 2022, 20:30:52 CET schrieb Mark Brown: > * PGP Signed by an unknown key > > On Wed, Sep 21, 2022 at 09:10:54AM +0200, Alexander Stein wrote: > > Having no cache defaults is not a mistake, especially for devices > > which do have some kind of strapping values which can't be provided > > statically. For this case a warning is the wrong log level, the initial > > cache values do need to be read form hardware. Reduce level to info. > > > > if (!map->reg_defaults_raw) { > > > > bool cache_bypass = map->cache_bypass; > > > > - dev_warn(map->dev, "No cache defaults, reading back from HW\n"); > > + dev_info(map->dev, "No cache defaults, reading back from HW\n"); > > This is a warning which is only generated in the case where we have a > non-sparse cache where we won't read from the hardware in the csae of > missing values and will instead just substitute zero as a default value. > It's warning that we might end up changing values for the device > unexpectedly in the case of a read/modify/write cycle that doesn't > actually check what the device currently has set. > > In this case if you can't use a rbtree cache I would recommend > bootstrapping by initially reading without a cache first to get the > default values, then replacing the regmap with one that uses the > defaults you just read. You'll need some care over suspend/resume > though.
The driver I'm working on clk-renesas-pcie.c only has 8 registers, so there is no benefit to use a different cache than REGCACHE_FLAT.
But I currently fail to see why this is only for non-sparse caches. This is printed even before the cache_ops init() is called.
Before the call to regcache_hw_init() there is this comment: > /* Some devices such as PMICs don't have cache defaults, > * we cope with this by reading back the HW registers and > * crafting the cache defaults by hand. > */
This is exactly what I want to do: Read back HW registers and create a cache. Actually regcache_hw_init() is exactly doing what you are suggesting: 1. reading HW registers into map->reg_defaults_raw 2. a) copy them into map->reg_defaults b) read HW register individually if 1. failed
So thinking more about this, this warning should be removed altogether IMHO.
Best regards, Alexander
| |