On Sun, Apr 21, 2019 at 10:26:40AM +0300, Daniel Baluta wrote:
Firstly, according to your commit message, neither imx8qm nor imx6sx has an "mclk0" clock in the clock list. Either of them starts with "mclk1". So, before you change the driver, I don't think it's even a right thing to define an "mclk0" in the DT.
From what I understand mclk0 means option 00b of MSEL bits which is:
- busclk for i.MX8
- mclk1 for i.MX6/7.
MSEL bit is used for an internal clock MUX to select four clock inputs. However, these four clock inputs aren't exactly 1:1 of SAI's inputs. As fas as I can tell, SAI only has one bus clock and three MCLK[1-3]; the internal clock MUX maps the bus clock or MCLK1 to its input0, and then linearly maps MCLK[1-3] to its inputs[1-3]. So it doesn't sound right to me that you define an "MCLK0" in the DT, as it's supposed to describe input clocks of SAI block, other than its internal clock MUX's.
Adding a mclk0 in the DT and making it point to the correct option (busclk or mclk1) does no harm as the driver doesn't yet parse mclk0.
I know it's making driver easier, but unfortunately it's not a right thing to do from my point of view.
sai->mclk_clk[i] = devm_clk_get(&pdev->dev, tmp); if (IS_ERR(sai->mclk_clk[i])) {Secondly, this would break existing DT bindings of imx6sx and imx7 platforms as they both have clock-names defined in DTB: clock-names = "bus", "mclk1", "mclk2", "mclk3"; Since there's no "mclk0", the entire probe() would error-out.
Not exactly. The probe won't error-out. It will just print a warning message
You're right about this part. I didn't look further as the patch ends at the IS_ERR, so made a wrong assumption. Sorry.
In my opinion, the current implementation of fsl_sai has a bug for imx6/7.
Currently, fsl_sai.c driver does:
sai->mclk_clk[0] = sai->bus_clk;is wrong, because on imx6/7 mclk_clk[0] should point to the same clk as mclk_clk[1]
You are right. It should be fixed, but not by this approach IMHO.
Thanks