Re: [PATCH v8 2/2] omap hsmmc: adaptation of sdma descriptor autoloading feature

[Venkatraman S <svenkatr@ti.com>]

Nishanth Menon <menon.nishanth@gmail.com> wrote:
> On 05/09/2010 05:51 AM, Venkatraman S wrote:
>>
>> Nishanth Menon<nm@ti.com>  wrote:
>>>
>>> Chikkature Rajashekar, Madhusudhan had written, on 05/07/2010 11:59 AM,
>>> the
>>> following:
>>>>
>>>>>
>>>>>>>> Subject: Re: [PATCH v8 2/2] omap hsmmc: adaptation of sdma
>>>>>
>>>>> descriptor
>>>>>>>
>>>>>>> autoloading feature
>>>>>>>>
>>>>>>>> <<snip>>
>>>>>>>>
>>>>>>>>>> I am not clear about the method. The board files export the
>>>>>>>>>> omap_mmc_platform_data.
>>>>>>>>>> Does it imply that all board files have to change and export
>>>>>>>>>> the capability so that it can be queried ?
>>>>>>>>>
>>>>>>>>> No. You don't have to modify the board files. This would need
>>>>>>>>> change in devices.c which common for all omap boards.
>>>>>>>>>
>>>>>>>>> I don't have a strong opinion on this point but just put forth an
>>>>>>>>> alternate way to avoid such SOC specific check in drivers.
>>>>>>>>> You can take call on this
>>>>>>>>
>>>>>>>> Agree. How about adding a flag in hsmmc.h&  omap_mmc_platform_data,
>>>>>>>> that would take care of SDMA&  SDMA_DLAOD in the driver instead
>>>>>
>>>>> going
>>>>>>>>
>>>>>>>> with SOC check .
>>>>>>>
>>>>>>> Good idea Kishore.
>>>>>>> Venkat,
>>>>>>> Can you do what kishore is suggesting.
>>>>>>>
>>>>>> omap_mmc_platform_data is MMC specific platform data. Why add a SDMA
>>>>>> specific feature capability into it? Even though you add it there, you
>>>>>
>>>>> will
>>>>>>
>>>>>> still need to have a cpu check before that can be set in a common
>>>>>> code.
>>>>>>
>>>>> CPU checks are allowed to be in the platform files. That is where such
>>>>> machine/SOC specific differentiation should be done and not in the
>>>>> device
>>>>> drivers.
>>>>> That way device drivers remains clean and portable.
>>>>>
>>>>> I want to stop this thread here since neither the patch author nor the
>>>>> file
>>>>> maintainer thinks that cpu checks in the device drivers is bad idea.
>>>>>
>>>>> Please decide within yourself and move on.
>>>>>
>>>>
>>>> I am not saying that it is wrong. My point here is that adding this
>>>> particular flag into MMC platform data to differentiate a SDMA specific
>>>> feature which got introduced post certain SOC may not be needed. But you
>>>> can
>>>> always post your comments on the list which will be looked at by a wider
>>>> audience and finally the right patch will go in.
>>>
>>> Please see [1] for SOC specific feature handling. any reasons we can't
>>> handle it by adding a new feature?
>>>
>>> [1]
>>>
>>> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=arch/arm/plat-omap/include/plat/cpu.h#l439
>>>
>>
>> Thanks. I can add a new feature here, but I see that the API is tied
>> to OMAP3, whereas the DMA feature is common
>> to 3630, OMAP4 and mostly everything after that. I can work on an
>> upgrade, but do you see that
>> as a dependency and done on the context of this patch ?
>> Regards,
>> Venkat.
>
> Yes, I am aware that the current APIs are tied to OMAP3, no reason that we
> cant introduce a OMAP version independent feature.. Yes, IMHO, this is an
> SOC specific feature that has no place in a platform data.. lets not misuse
> that.
> Regards,
> NM


Draft patch for this is here (Tested ok). I will post this as part of
the series if this looks ok...
This doesn't have all existing feature checks for OMAP4, but they seem to be not
needed/used anyway..

---
 arch/arm/mach-omap2/clock3xxx_data.c  |    2 -
 arch/arm/mach-omap2/id.c              |   25 +++++++++++++++--------
 arch/arm/plat-omap/include/plat/cpu.h |   36 +++++++++++++++++-----------------
 3 files changed, 36 insertions(+), 27 deletions(-)

Index: linux-omap-2.6/arch/arm/mach-omap2/id.c
===================================================================
--- linux-omap-2.6.orig/arch/arm/mach-omap2/id.c	2010-05-09
23:29:28.000000000 +0530
+++ linux-omap-2.6/arch/arm/mach-omap2/id.c	2010-05-10 17:39:29.000000000 +0530
@@ -28,7 +28,7 @@
 static struct omap_chip_id omap_chip;
 static unsigned int omap_revision;

-u32 omap3_features;
+u32 omap_features;

 unsigned int omap_rev(void)
 {
@@ -161,14 +161,14 @@
 #define OMAP3_CHECK_FEATURE(status,feat)				\
 	if (((status & OMAP3_ ##feat## _MASK) 				\
 		>> OMAP3_ ##feat## _SHIFT) != FEAT_ ##feat## _NONE) { 	\
-		omap3_features |= OMAP3_HAS_ ##feat;			\
+		omap_features |= OMAP_HAS_ ##feat;			\
 	}

 void __init omap3_check_features(void)
 {
 	u32 status;

-	omap3_features = 0;
+	omap_features = 0;

 	status = omap_ctrl_readl(OMAP3_CONTROL_OMAP_STATUS);

@@ -178,7 +178,7 @@
 	OMAP3_CHECK_FEATURE(status, NEON);
 	OMAP3_CHECK_FEATURE(status, ISP);
 	if (cpu_is_omap3630())
-		omap3_features |= OMAP3_HAS_192MHZ_CLK;
+		omap_features |= OMAP_HAS_192MHZ_CLK | OMAP_HAS_SDMA_DLOAD;

 	/*
 	 * TODO: Get additional info (where applicable)
@@ -267,6 +267,12 @@
 	}
 }

+void __init omap4_check_features(void)
+{
+	omap_features = OMAP_HAS_SDMA_DLOAD;
+
+}
+
 void __init omap4_check_revision(void)
 {
 	u32 idcode;
@@ -294,7 +300,7 @@
 }

 #define OMAP3_SHOW_FEATURE(feat)		\
-	if (omap3_has_ ##feat())		\
+	if (omap_has_ ##feat())		\
 		printk(#feat" ");

 void __init omap3_cpuinfo(void)
@@ -314,20 +320,20 @@
 		/*
 		 * AM35xx devices
 		 */
-		if (omap3_has_sgx()) {
+		if (omap_has_sgx()) {
 			omap_revision = OMAP3517_REV(rev);
 			strcpy(cpu_name, "AM3517");
 		} else {
 			/* Already set in omap3_check_revision() */
 			strcpy(cpu_name, "AM3505");
 		}
-	} else if (omap3_has_iva() && omap3_has_sgx()) {
+	} else if (omap_has_iva() && omap_has_sgx()) {
 		/* OMAP3430, OMAP3525, OMAP3515, OMAP3503 devices */
 		strcpy(cpu_name, "OMAP3430/3530");
-	} else if (omap3_has_iva()) {
+	} else if (omap_has_iva()) {
 		omap_revision = OMAP3525_REV(rev);
 		strcpy(cpu_name, "OMAP3525");
-	} else if (omap3_has_sgx()) {
+	} else if (omap_has_sgx()) {
 		omap_revision = OMAP3515_REV(rev);
 		strcpy(cpu_name, "OMAP3515");
 	} else {
@@ -386,6 +392,7 @@
 		return;
 	} else if (cpu_is_omap44xx()) {
 		omap4_check_revision();
+		omap4_check_features();
 		return;
 	} else {
 		pr_err("OMAP revision unknown, please fix!\n");
Index: linux-omap-2.6/arch/arm/plat-omap/include/plat/cpu.h
===================================================================
--- linux-omap-2.6.orig/arch/arm/plat-omap/include/plat/cpu.h	2010-05-09
23:24:15.000000000 +0530
+++ linux-omap-2.6/arch/arm/plat-omap/include/plat/cpu.h	2010-05-10
17:53:04.000000000 +0530
@@ -434,28 +434,30 @@
 void omap2_check_revision(void);

 /*
- * Runtime detection of OMAP3 features
+ * Runtime detection of OMAP features
  */
-extern u32 omap3_features;
+extern u32 omap_features;

-#define OMAP3_HAS_L2CACHE		BIT(0)
-#define OMAP3_HAS_IVA			BIT(1)
-#define OMAP3_HAS_SGX			BIT(2)
-#define OMAP3_HAS_NEON			BIT(3)
-#define OMAP3_HAS_ISP			BIT(4)
-#define OMAP3_HAS_192MHZ_CLK		BIT(5)
+#define OMAP_HAS_L2CACHE		BIT(0)
+#define OMAP_HAS_IVA			BIT(1)
+#define OMAP_HAS_SGX			BIT(2)
+#define OMAP_HAS_NEON			BIT(3)
+#define OMAP_HAS_ISP			BIT(4)
+#define OMAP_HAS_192MHZ_CLK		BIT(5)
+#define OMAP_HAS_SDMA_DLOAD		BIT(6)

-#define OMAP3_HAS_FEATURE(feat,flag)			\
-static inline unsigned int omap3_has_ ##feat(void)	\
+#define OMAP_HAS_FEATURE(feat, flag)			\
+static inline unsigned int omap_has_ ##feat(void)	\
 {							\
-	return (omap3_features & OMAP3_HAS_ ##flag);	\
+	return (omap_features & OMAP_HAS_ ##flag);	\
 }							\

-OMAP3_HAS_FEATURE(l2cache, L2CACHE)
-OMAP3_HAS_FEATURE(sgx, SGX)
-OMAP3_HAS_FEATURE(iva, IVA)
-OMAP3_HAS_FEATURE(neon, NEON)
-OMAP3_HAS_FEATURE(isp, ISP)
-OMAP3_HAS_FEATURE(192mhz_clk, 192MHZ_CLK)
+OMAP_HAS_FEATURE(l2cache, L2CACHE)
+OMAP_HAS_FEATURE(sgx, SGX)
+OMAP_HAS_FEATURE(iva, IVA)
+OMAP_HAS_FEATURE(neon, NEON)
+OMAP_HAS_FEATURE(isp, ISP)
+OMAP_HAS_FEATURE(192mhz_clk, 192MHZ_CLK)
+OMAP_HAS_FEATURE(sdma_dload, SDMA_DLOAD)

 #endif
Index: linux-omap-2.6/arch/arm/mach-omap2/clock3xxx_data.c
===================================================================
--- linux-omap-2.6.orig/arch/arm/mach-omap2/clock3xxx_data.c	2010-05-10
14:41:39.000000000 +0530
+++ linux-omap-2.6/arch/arm/mach-omap2/clock3xxx_data.c	2010-05-10
14:41:50.000000000 +0530
@@ -3510,7 +3510,7 @@
 			cpu_clkflg |= CK_3430ES2;
 		}
 	}
-	if (omap3_has_192mhz_clk())
+	if (omap_has_192mhz_clk())
 		omap_96m_alwon_fck = omap_96m_alwon_fck_3630;

 	if (cpu_is_omap3630()) {
--
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