Dear Eugeniu-san,
Thank you for your comments!
From: Eugeniu Rosca, Sent: Tuesday, October 29, 2019 11:38 PM
Dear Shimoda-san, dear reviewers,
On Fri, Oct 11, 2019 at 01:50:32PM +0900, Yoshihiro Shimoda wrote:
According to the R-Car Gen2/3 manual, the bit 0 of MACCTLR register should be written to 0 before enabling PCIETCTLR.CFINIT because the bit 0 is set to 1 on reset. To avoid unexpected behaviors from this incorrect setting, this patch fixes it.
Your development and reviewing effort to reach v4 is very appreciated.
However, in the context of some internal reviews of this patch, we are having hard times reconciling the change with our (possibly incomplete or inaccurate) interpretation of the R-Car3 HW User’s Manual (Rev.2.00 Jul 2019). The latter says in Chapter "54. PCIE Controller" / "(2) Initial Setting of PCI Express":
----snip---- Be sure to write the initial value (= H'80FF 0000) to MACCTLR before enabling PCIETCTLR.CFINIT. ----snip----
Is my assumption correct that the description of this patch is a rewording of the above quote from the manual <snip>
You are correct. Since the reset value of MACCTLR is H'80FF 0001, I thought clearing the LSB bit was enough. However, as your situation, I think I should have described the above quote from the manual and have such a code (writing the value instead of clearing the LSB only).
If it is only the LSB which "should be written to 0 before enabling PCIETCTLR.CFINIT", would you agree that the statement quoted from the manual would better be rephrased appropriately? TIA.
As I mentioned above, I think the above quote from the manual is better than rephrased.
Sergei, Geert-san, I think we should revert this patch and fix code/commit log to follow the manual. What do you think?
Best regards, Yoshihiro Shimoda
Fixes: c25da4778803 ("PCI: rcar: Add Renesas R-Car PCIe driver") Fixes: be20bbcb0a8c ("PCI: rcar: Add the initialization of PCIe link in resume_noirq()") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com Reviewed-by: Sergei Shtylyov sergei.shtylyov@cogentembedded.com Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be
-- Best Regards, Eugeniu