V4L/DVB: dib3000mc: reduce large stack usage

This patch reduces static stack usage of one of the 2 top offenders
as listed by 'make checkstack':

Building with CONFIG_FRAME_WARN=2048 produces:

drivers/media/dvb/frontends/dib3000mc.c:853: warning: the frame size of 2224 bytes is larger than 2048 bytes

and in 'make checkstack', the stack usage goes from:
0x00000bbd dib3000mc_i2c_enumeration [dib3000mc]:	2232
to unlisted with this patch.

I don't have the hardware that is needed to test this patch.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Patrick Boettcher <pboettcher@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 22 insertions, 13 deletions

diff --git a/drivers/media/dvb/frontends/dib3000mc.c b/drivers/media/dvb/frontends/dib3000mc.c
index 40a099810279..afad252abf41 100644
--- a/drivers/media/dvb/frontends/dib3000mc.c
+++ b/drivers/media/dvb/frontends/dib3000mc.c
@@ -814,42 +814,51 @@ EXPORT_SYMBOL(dib3000mc_set_config);
 
 int dib3000mc_i2c_enumeration(struct i2c_adapter *i2c, int no_of_demods, u8 default_addr, struct dib3000mc_config cfg[])
 {
-        struct dib3000mc_state st = { .i2c_adap = i2c };
+        struct dib3000mc_state *dmcst;
         int k;
         u8 new_addr;
 
         static u8 DIB3000MC_I2C_ADDRESS[] = {20,22,24,26};
 
+        dmcst = kzalloc(sizeof(struct dib3000mc_state), GFP_KERNEL);
+        if (dmcst == NULL)
+                return -ENODEV;
+
+        dmcst->i2c_adap = i2c;
+
         for (k = no_of_demods-1; k >= 0; k--) {
-                st.cfg = &cfg[k];
+                dmcst->cfg = &cfg[k];
 
                 /* designated i2c address */
                 new_addr          = DIB3000MC_I2C_ADDRESS[k];
-                st.i2c_addr = new_addr;
-                if (dib3000mc_identify(&st) != 0) {
-                        st.i2c_addr = default_addr;
-                        if (dib3000mc_identify(&st) != 0) {
+                dmcst->i2c_addr = new_addr;
+                if (dib3000mc_identify(dmcst) != 0) {
+                        dmcst->i2c_addr = default_addr;
+                        if (dib3000mc_identify(dmcst) != 0) {
                                 dprintk("-E-  DiB3000P/MC #%d: not identified\n", k);
+                                kfree(dmcst);
                                 return -ENODEV;
                         }
                 }
 
-                dib3000mc_set_output_mode(&st, OUTMODE_MPEG2_PAR_CONT_CLK);
+                dib3000mc_set_output_mode(dmcst, OUTMODE_MPEG2_PAR_CONT_CLK);
 
                 // set new i2c address and force divstr (Bit 1) to value 0 (Bit 0)
-                dib3000mc_write_word(&st, 1024, (new_addr << 3) | 0x1);
-                st.i2c_addr = new_addr;
+                dib3000mc_write_word(dmcst, 1024, (new_addr << 3) | 0x1);
+                dmcst->i2c_addr = new_addr;
         }
 
         for (k = 0; k < no_of_demods; k++) {
-                st.cfg = &cfg[k];
-                st.i2c_addr = DIB3000MC_I2C_ADDRESS[k];
+                dmcst->cfg = &cfg[k];
+                dmcst->i2c_addr = DIB3000MC_I2C_ADDRESS[k];
 
-                dib3000mc_write_word(&st, 1024, st.i2c_addr << 3);
+                dib3000mc_write_word(dmcst, 1024, dmcst->i2c_addr << 3);
 
                 /* turn off data output */
-                dib3000mc_set_output_mode(&st, OUTMODE_HIGH_Z);
+                dib3000mc_set_output_mode(dmcst, OUTMODE_HIGH_Z);
         }
+
+        kfree(dmcst);
         return 0;
 }
 EXPORT_SYMBOL(dib3000mc_i2c_enumeration);