On 12/07/16 13:22, Russell King - ARM Linux wrote:
On Thu, Jun 30, 2016 at 05:13:33PM +0300, Tero Kristo wrote:/** + * ti_clk_get - lookup a TI clock handle + * @dev_id: device to lookup clock for + * @con_id: connection ID to find + * + * Searches for a TI clock handle based on the DT node name. + * Returns the pointer to the clock handle, or ERR_PTR in failure. + */ +static struct clk *ti_clk_get(const char *dev_id, const char *con_id) +{ + struct of_phandle_args clkspec; + struct device_node *node; + struct clk *clk; + + /* Only check for cases of type clk_get_sys(NULL, "xyz") */ + if (dev_id || !con_id) + return ERR_PTR(-ENOENT); + + if (of_have_populated_dt()) { + node = of_find_node_by_name(NULL, con_id); + clkspec.np = node; + clk = of_clk_get_from_provider(&clkspec); + + if (!IS_ERR(clk)) + return clk; + } + + return ERR_PTR(-ENOENT); +}I _really_ don't like this. This takes us back to the totally broken idea, that's already been proven to be greatly harmful in OMAP land, that the "con_id" is not a _DEVICE SPECIFIC CONNECTION NAME_ but is a CLOCK NAME. The connection ID is supposed to be a static string in the requestor of the clock, not some random string picked out from DT.
What is the harm in that actually? I have most likely missed some discussion but please educate me. The problem is, we are already using this convention all over the place in the kernel (not only OMAPs), and trying to clean up the kernel requires some intermediate steps being taken, otherwise we end up doing all the clean-ups in a single massive patch I fear (change all the hwmod data + clock data + any implementations related to these at the same time.)
This specific implementation should be possible to deprecate later once the hwmod database is gone btw, and is mostly required for hwmod data only (+ OMAP timer implementation, maybe some others.) The biggest abuser of clk_get interface atm is omap-hwmod.
This series started out with the assertion that the new clkdev hook was to avoid registering lots of clock aliases, but it seems with this patch we're going to end up with lots of specifically named nodes in DT instead. It's just moving the problem to somewhere else.
That is true, it will end up adding new DT nodes. However, as OMAP already is doing this extensively, I wonder what would be the alternative. Maybe move all the clock data back to kernel space to increase the size of multi-v7 builds?
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