On Monday 05 August 2013 02:41 PM, Tomi Valkeinen wrote:
On 02/08/13 17:03, Archit Taneja wrote:
Create functions which the VPE driver can use to create a VPDMA descriptor and
add it to a VPDMA descriptor list. These functions take a pointer to an existing
list, and append the configuration/data/control descriptor header to the list.
In the case of configuration descriptors, the creation of a payload block may be
required(the payloads can hold VPE MMR values, or scaler coefficients). The
allocation of the payload buffer and it's content is left to the VPE driver.
However, the VPDMA library provides helper macros to create payload in the
correct format.
Add debug functions to dump the descriptors in a way such that it's easy to see
the values of different fields in the descriptors.
There are lots of defines and inline functions in this patch. But at
least the ones I looked at were only used once.
For example, dtd_set_xfer_length_height() is called only in one place.
Then dtd_set_xfer_length_height() uses DTD_W1(), and again it's the only
place where DTD_W1() is used.
So instead of:
dtd_set_xfer_length_height(dtd, c_rect->width, height);
You could as well do:
dtd->xfer_length_height = (c_rect->width << DTD_LINE_LENGTH_SHFT) | height;
Now, presuming the compiler optimizes correctly, there should be no
difference between the two options above. My only point is that I wonder
if having multiple "layers" there improves readability at all. Some
helper funcs are rather trivial, like:
+static inline void dtd_set_w1(struct vpdma_dtd *dtd, u32 value)
+{
+ dtd->w1 = value;
+}
Then there are some, like dtd_set_type_ctl_stride(), that contains lots
of parameters. Hmm, okay, dtd_set_type_ctl_stride() is called in two
places, so at least in that case it makes sense to have that helper
func. But dtd_set_type_ctl_stride() uses DTD_W0(), and that's again the
only place where it's used.
So, I don't know. I'm not suggesting to change anything, I just started
wondering if all those macros and helpers actually help or not.
There are some more descriptors to add later on, but you are right about
many of them being used at only one place, I'll have a look at the
macros again.
Signed-off-by: Archit Taneja <archit@xxxxxx>
---
drivers/media/platform/ti-vpe/vpdma.c | 269 +++++++++++
drivers/media/platform/ti-vpe/vpdma.h | 48 ++
drivers/media/platform/ti-vpe/vpdma_priv.h | 695 +++++++++++++++++++++++++++++
3 files changed, 1012 insertions(+)
diff --git a/drivers/media/platform/ti-vpe/vpdma.c b/drivers/media/platform/ti-vpe/vpdma.c
index b15b3dd..b957381 100644
--- a/drivers/media/platform/ti-vpe/vpdma.c
+++ b/drivers/media/platform/ti-vpe/vpdma.c
@@ -21,6 +21,7 @@
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/videodev2.h>
#include "vpdma.h"
#include "vpdma_priv.h"
@@ -425,6 +426,274 @@ int vpdma_submit_descs(struct vpdma_data *vpdma, struct vpdma_desc_list *list)
return 0;
}
+static void dump_cfd(struct vpdma_cfd *cfd)
+{
+ int class;
+
+ class = cfd_get_class(cfd);
+
+ pr_debug("config descriptor of payload class: %s\n",
+ class == CFD_CLS_BLOCK ? "simple block" :
+ "address data block");
+
+ if (class == CFD_CLS_BLOCK)
+ pr_debug("word0: dst_addr_offset = 0x%08x\n",
+ cfd_get_dest_addr_offset(cfd));
+
+ if (class == CFD_CLS_BLOCK)
+ pr_debug("word1: num_data_wrds = %d\n", cfd_get_block_len(cfd));
+
+ pr_debug("word2: payload_addr = 0x%08x\n", cfd_get_payload_addr(cfd));
+
+ pr_debug("word3: pkt_type = %d, direct = %d, class = %d, dest = %d, "
+ "payload_len = %d\n", cfd_get_pkt_type(cfd),
+ cfd_get_direct(cfd), class, cfd_get_dest(cfd),
+ cfd_get_payload_len(cfd));
+}
There's quite a bit of code in these dump functions, and they are always
called. I'm sure getting that data is good for debugging, but I presume
they are quite useless for normal use. So I think they should be
compiled in only if some Kconfig option is selected.
Won't pr_debug() functions actually print something only when
CONFIG_DYNAMIC_DEBUG is selected or if the DEBUG is defined? They will
still consume a lot of code, but it would just end up in dummy printk
calls, right?
+/*
+ * data transfer descriptor
+ *
+ * All fields are 32 bits to make them endian neutral
What does that mean? Why would 32bit fields make it endian neutral?
Each 32 bit field describes one word of the data descriptor. Each
descriptor has a number of parameters.
If we look at the word 'xfer_length_height'. It's composed of height
(from bits 15:0) and width(from bits 31:16). If the word was expressed
using bit fields, we can describe the word(in big endian) as:
struct vpdma_dtd {
...
unsigned int xfer_width:16;
unsigned int xfer_height:16;
...
...
};
and in little endian as:
struct vpdma_dtd {
...
unsigned int xfer_height:16;
unsigned int xfer_width:16;
...
...
};
So this representation makes it endian dependent. Maybe the comment
should be improved saying that usage of u32 words instead of bit fields
prevents endian issues.
+ */
+struct vpdma_dtd {
+ u32 type_ctl_stride;
+ union {
+ u32 xfer_length_height;
+ u32 w1;
+ };
+ dma_addr_t start_addr;
+ u32 pkt_ctl;
+ union {
+ u32 frame_width_height; /* inbound */
+ dma_addr_t desc_write_addr; /* outbound */
Are you sure dma_addr_t is always 32 bit?
I am not sure about this.
+ };
+ union {
+ u32 start_h_v; /* inbound */
+ u32 max_width_height; /* outbound */
+ };
+ u32 client_attr0;
+ u32 client_attr1;
+};
I'm not sure if I understand the struct right, but presuming this one
struct is used for both writing and reading, and certain set of fields
is used for writes and other set for reads, would it make sense to have
two different structs, instead of using unions? Although they do have
many common fields, and the unions are a bit scattered there, so I don't
know if that would be cleaner...
It helps in a having a common debug function, I don't see much benefit
apart from that. I'll see if it's better to have them as separate structs.
Thanks,
Archit
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