| Message ID | 1375337800-2605-1-git-send-email-b.brezillon@overkiz.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 1 Aug 2013, Boris BREZILLON wrote: > The AT91 PMC (Power Management Controller) provides an USB clock used by > USB Full Speed host (ohci) and USB Full Speed device (udc). > The usb drivers (ohci and udc) must configure this clock to 48Mhz. > This configuration was formely done in mach-at91/clock.c, but this > implementation will be removed when moving to common clk framework. > > This patch adds support for usb clock retrieval and configuration, and is > backward compatible with the current at91 clk implementation (if usb clk > is not found, it does not configure/enable it). > > Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com> > @@ -163,6 +169,8 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver, > goto err5; > } > > + uclk = clk_get(&pdev->dev, "usb_clk"); What happens if uclk isn't found but it is needed? Alan Stern
On 01/08/2013 16:39, Alan Stern wrote: > On Thu, 1 Aug 2013, Boris BREZILLON wrote: > >> The AT91 PMC (Power Management Controller) provides an USB clock used by >> USB Full Speed host (ohci) and USB Full Speed device (udc). >> The usb drivers (ohci and udc) must configure this clock to 48Mhz. >> This configuration was formely done in mach-at91/clock.c, but this >> implementation will be removed when moving to common clk framework. >> >> This patch adds support for usb clock retrieval and configuration, and is >> backward compatible with the current at91 clk implementation (if usb clk >> is not found, it does not configure/enable it). >> >> Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com> >> @@ -163,6 +169,8 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver, >> goto err5; >> } >> >> + uclk = clk_get(&pdev->dev, "usb_clk"); > What happens if uclk isn't found but it is needed? It will not fail but I guess the usb host won't work as the clock won't be correctly configured. I agree with you: this is not a good solution. Another option is to keep the previous version of this patch and put uclk handling in "#ifdef CONFIG_COMMON_CLK #endif" sections. Would this be acceptable ? > > Alan Stern >
On Thu, 1 Aug 2013, boris brezillon wrote: > > What happens if uclk isn't found but it is needed? > It will not fail but I guess the usb host won't work as the clock won't > be correctly > configured. > > I agree with you: this is not a good solution. > > Another option is to keep the previous version of this patch and put > uclk handling > in "#ifdef CONFIG_COMMON_CLK #endif" sections. > > Would this be acceptable ? Yes. However, a more elegant approach is to protect the relevant statements with: if (defined(CONFIG_COMMON_CLK)). This preprocessor evaluates this to a 0 or 1, so the compiler will not generate output for the protected source code if the symbol isn't defined. Alan Stern
Hello. On 08/01/2013 07:56 PM, Alan Stern wrote: >>> What happens if uclk isn't found but it is needed? >> It will not fail but I guess the usb host won't work as the clock won't >> be correctly >> configured. >> I agree with you: this is not a good solution. >> Another option is to keep the previous version of this patch and put >> uclk handling >> in "#ifdef CONFIG_COMMON_CLK #endif" sections. >> Would this be acceptable ? > Yes. However, a more elegant approach is to protect the relevant > statements with: if (defined(CONFIG_COMMON_CLK)). This preprocessor You probably meant IS_ENABLED() or IS_BUIILTIN()? Or is there something I don't know about gcc preprocessor? > evaluates this to a 0 or 1, so the compiler will not generate output > for the protected source code if the symbol isn't defined. > Alan Stern WBR, Sergei
diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c index 9677f68..913d293 100644 --- a/drivers/usb/host/ohci-at91.c +++ b/drivers/usb/host/ohci-at91.c @@ -31,8 +31,8 @@ #define at91_for_each_port(index) \ for ((index) = 0; (index) < AT91_MAX_USBH_PORTS; (index)++) -/* interface and function clocks; sometimes also an AHB clock */ -static struct clk *iclk, *fclk, *hclk; +/* interface, function and usb clocks; sometimes also an AHB clock */ +static struct clk *iclk, *fclk, *uclk, *hclk; static int clocked; extern int usb_disabled(void); @@ -41,6 +41,10 @@ extern int usb_disabled(void); static void at91_start_clock(void) { + if (!IS_ERR(uclk)) { + clk_set_rate(uclk, 48000000); + clk_prepare_enable(uclk); + } clk_prepare_enable(hclk); clk_prepare_enable(iclk); clk_prepare_enable(fclk); @@ -52,6 +56,8 @@ static void at91_stop_clock(void) clk_disable_unprepare(fclk); clk_disable_unprepare(iclk); clk_disable_unprepare(hclk); + if (!IS_ERR(uclk)) + clk_disable_unprepare(uclk); clocked = 0; } @@ -163,6 +169,8 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver, goto err5; } + uclk = clk_get(&pdev->dev, "usb_clk"); + at91_start_hc(pdev); ohci_hcd_init(hcd_to_ohci(hcd)); @@ -173,6 +181,9 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver, /* Error handling */ at91_stop_hc(pdev); + if (!IS_ERR(uclk)) + clk_put(uclk); + clk_put(hclk); err5: clk_put(fclk); @@ -212,6 +223,8 @@ static void usb_hcd_at91_remove(struct usb_hcd *hcd, release_mem_region(hcd->rsrc_start, hcd->rsrc_len); usb_put_hcd(hcd); + if (!IS_ERR(uclk)) + clk_put(uclk); clk_put(hclk); clk_put(fclk); clk_put(iclk);
The AT91 PMC (Power Management Controller) provides an USB clock used by USB Full Speed host (ohci) and USB Full Speed device (udc). The usb drivers (ohci and udc) must configure this clock to 48Mhz. This configuration was formely done in mach-at91/clock.c, but this implementation will be removed when moving to common clk framework. This patch adds support for usb clock retrieval and configuration, and is backward compatible with the current at91 clk implementation (if usb clk is not found, it does not configure/enable it). Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com> --- drivers/usb/host/ohci-at91.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)